Deck 6: Discrete Probability Distributions

Question 1

The standard deviation of any uniform probability distribution is

A) (b - a)/2
B) n(1 - π)
C)
D)

Answer 1

Question 2

The upper and lower limits of a uniform probability distribution are

A) positive and negative infinity.
B) plus and minus three standard deviations.
C) 0 and 1.
D) the maximum and minimum values of the random variable.

Answer 2

the maximum and minimum values of the random variable.

Question 3

i. Asymptotic, means that the normal curve gets closer and closer to the X-axis but never actually
Touches it.
ii. When referring to the normal probability function, there is not just one of them; there is a "family"
Of them.
iii. Some normal probability distributions have equal arithmetic means, but their standard deviations
May be different.

A) (i), (ii), and (iii) are all correct statements.
B) (i) is a correct statement but not (ii) or (iii).
C) (i) and (iii) are correct statements but not (ii).
D) (ii) and (iii) are correct statements but not (i).
E) (i), (ii), and (iii) are all false statements.

Answer 3

(i), (ii), and (iii) are all correct statements.

Question 4

The shape of any uniform probability distribution is

A) Negatively skewed
B) Positively skewed
C) Rectangular
D) Bell shaped

Question 5

What is an important similarity between the uniform and normal probability distributions?

A) The mean, median and mode are all equal.
B) The mean and median are equal.
C) They are negatively skewed.
D) About 68% of all observations are within one standard deviation of the mean.

Question 6

i. Areas within a continuous probability distribution represent probabilities.
ii. The Empirical Rule of probability can be applied to the uniform probability distribution.
iii. The total area within a continuous probability distribution is equal to 100.

A) (i), (ii), and (iii) are all correct statements.
B) (i) is a correct statement but not (ii) or (iii).
C) (i) and (iii) are correct statements but not (ii).
D) (ii) and (iii) are correct statements but not (i).
E) (i), (ii), and (iii) are all false statements.

Question 7

i. For any uniform probability distribution, the mean and standard deviation can be computed by
Knowing the maximum and minimum values of the random variable.
ii. In a uniform probability distribution, P(x) is constant between the distribution's minimum and
Maximum values.
iii. The uniform probability distribution's shape is a rectangle.

A) (i), (ii), and (iii) are all correct statements.
B) (i) is a correct statement but not (ii) or (iii).
C) (i) and (iii) are correct statements but not (ii).
D) (ii) and (iii) are correct statements but not (i).
E) (i), (ii), and (iii) are all false statements.

Question 8

i. The uniform probability distribution's shape is a rectangle.
ii. The uniform probability distribution is symmetric about the mode.
iii. In a uniform probability distribution, P(x) is constant between the distribution's minimum and
Maximum values.

A) (i), (ii), and (iii) are all correct statements.
B) (i) is a correct statement but not (ii) or (iii).
C) (i) and, (iii) are correct statements but not (ii).
D) (ii) and, (iii) are correct statements but not (i).
E) (i), (ii), and (iii) are all false statements.

Question 9

i. The Empirical Rule of probability can be applied to the uniform probability distribution.
ii. Areas within a continuous probability distribution represent probabilities.
iii. The total area within a continuous probability distribution is equal to 1.

A) (i), (ii), and (iii) are all correct statements.
B) (i) is a correct statement but not (ii) or (iii).
C) (i) and (iii) are correct statements but not (ii).
D) (ii) and (iii) are correct statements but not (i).
E) (i), (ii), and (iii) are all false statements.

Question 10

A major credit card company has determined that customers charge between $100 and $1,100 per
Month. Given that the average monthly amount charged is uniformly distributed, what is the
Probability that a person charges less than $200 per month?

A) 5%
B) 10%
C) 15%
D) 20%

Question 11

i. In a uniform probability distribution, P(x) is constant between the distribution's minimum and
Maximum values.
ii. For a uniform probability distribution, the probability of any event is equal to 1/(b-a).
iii. The uniform probability distribution is symmetric about the mode.

A) (i), (ii), and (iii) are all correct statements.
B) (i) is a correct statement but not (ii) or (iii).
C) (i) and (iii) are correct statements but not (ii).
D) (ii) and (iii) are correct statements but not (i).
E) (i), (ii), and (iii) are all false statements.

Question 12

i. Areas within a continuous probability distribution represent probabilities.
ii. The total area within any continuous probability distribution is equal to 1.00.
iii. For any discrete probability distribution, the probability, P(x), of any value of the random variable,
X, can be computed.

A) (i), (ii), and (iii) are all correct statements.
B) (i) is a correct statement but not (ii) or (iii).
C) (i) and (iii) are correct statements but not (ii).
D) (ii) and (iii) are correct statements but not (i).
E) (i), (ii), and (iii) are all false statements.

Question 13

i. The total area within any continuous probability distribution is equal to 1.00.
ii. For any continuous probability distribution, the probability, P(x), of any value of the random
Variable, X, can be computed.
iii. For any discrete probability distribution, the probability, P(x), of any value of the random variable,
X, can be computed.

A) (i), (ii), and (iii) are all correct statements.
B) (i) is a correct statement but not (ii) or (iii).
C) (i) and (iii) are correct statements but not (ii).
D) (ii) and (iii) are correct statements but not (i).
E) (i), (ii), and (iii) are all false statements.

Question 14

A financial advising company has determined that the price-to-earnings ratios for 20 randomly
Selected publicly traded companies range between 0.9 and 2.9. Given that the price-to-earnings
Ratios are uniformly distributed, what is the average price-to-earnings ratio?

A) 0.9
B) 1.9
C) 2.9
D) 3.8

Question 15

i. The uniform probability distribution's standard deviation is proportional to the distribution's range.
ii. The uniform probability distribution is symmetric about the mode.
iii. For a uniform probability distribution, the probability of any event is equal to 1/(b-a).

A) (i), (ii), and (iii) are all correct statements.
B) (i) is a correct statement but not (ii) or (iii).
C) (i) and (iii) are correct statements but not (ii).
D) (ii) and (iii) are correct statements but not (i).
E) (i), (ii), and (iii) are all false statements.

Question 16

A major credit card company has determined that customers charge between $100 and $1,100 per
Month. Given that the average monthly amount charged is uniformly distributed, what percent of
Monthly charges are between $600 and $889?

A) 28.9%
B) 20.8%
C) 26.2%
D) 29.3%

Question 17

The mean of any uniform probability distribution is

A) (b - a)/2
B) (a + b)/2
C)
D) nπ

Question 18

i. The uniform probability distribution is symmetric about the mean and median.
ii. The uniform probability distribution's shape is a rectangle.
iii. In a uniform probability distribution, P(x) is constant between the distribution's minimum and
Maximum values.

A) (i), (ii), and (iii) are all correct statements.
B) (i) is a correct statement but not (ii) or (iii).
C) (i) and (iii) are correct statements but not (ii).
D) (ii) and (iii) are correct statements but not (i).
E) (i), (ii), and (iii) are all false statements.

Question 19

A financial advising company has determined that the price-to-earnings ratios for 20 randomly
Selected publicly traded companies range between 0.9 and 2.9. Given that the price-to-earnings
Ratios are uniformly distributed, what percent of price-to-earnings ratios are between 1.90 and 2.48?

A) 19%
B) 20%
C) 26%
D) 29%

Question 20

A major credit card company has determined that customers charge between $100 and $1,100 per
Month. Given that the average monthly amount charged is uniformly distributed, what is the
Standard deviation of the monthly amount charged?

A) 298.67
B) 275.57
C) 267.88
D) 288.67

Question 21

i. In terms of a formula the standardized value of z is found by z = (X - µ)/σ.
ii. The standard normal distribution is a special normal distribution with a mean of 0 and a standard
Deviation of 1.
iii. A computed z for X values to the right of the mean is positive.

A) (i), (ii), and (iii) are all correct statements
B) (i) is a correct statement but not (ii) or (iii).
C) (i) and (iii) are correct statements but not (ii).
D) (i) and (ii) are correct statements but not (iii).
E) (i), (ii), and (iii) are all false statements.

Question 22

Two competitive brothers, who work in two different industries, were comparing their salaries.
Because there is a difference of 4 years in their respective work experience, they decided to
Compare, not their actual salaries, but to compare their salaries against their company averages to
See who is doing better. The following gives the brothers salaries, companies mean, and standard
Deviation for each company.
What is the z-score of Andy's salary?

A) - 1.29
B) 1.29
C) - 1.89
D) 1.89

Question 23

What is the distribution with a mean of 0 and a standard deviation of 1 called?

A) Frequency distribution
B) z-score
C) Standard normal distribution
D) Binomial probability distribution

Question 24

Which of the following is NOT a characteristic of the normal probability distribution?

A) Positively-skewed
B) Bell-shaped
C) Symmetrical
D) Asymptotic

Question 25

The mean of a normally distributed group of weekly incomes of a large group of executives is
$1,000 and the standard deviation is $100. What is the z-score for an income of $1,100?

A) 1.00
B) 2.00
C) 1.683
D) - 0.90

Question 26

Which of the following is NOT true regarding the normal distribution?

A) Mean, median and mode are all equal
B) It has a single peak
C) It is symmetrical
D) The points of the curve meet the X-axis at z = -3 and z = 3

Question 27

i. A z-score is the distance between a selected value (X) and the population mean (μ) divided by the
Population standard deviation (σ).
ii. The standard normal distribution is a special normal distribution with a mean of 0 and a standard
Deviation of 1.
iii. A computed z for X values to the right of the mean is negative.

A) (i), (ii), and (iii) are all correct statements.
B) (i) is a correct statement but not (ii) or (iii).
C) (i) and (iii) are correct statements but not (ii).
D) (i) and (ii) are correct statements but not (iii).
E) (i), (ii), and (iii) are all false statements.

Question 28

i. The normal curve falls off smoothly in either direction from the central value. Since it is asymptotic,
The curve gets closer and closer to the X-axis, but never actually touches it.
ii. The mean (µ) divides the normal curve into two identical halves.
iii. The number of different normal distributions is unlimited.

A) (i), (ii), and (iii) are all correct statements.
B) (i) is a correct statement but not (ii) or (iii).
C) (i) and (iii) are correct statements but not (ii).
D) (ii) and (iii) are correct statements but not (i).
E) (i), (ii), and (iii) are all false statements.

Question 29

i. In terms of a formula the standardized value of z is found by z = (X - µ)/σ.
ii. The standard normal distribution is a normal distribution with a mean of 0 and a standard
Deviation of less than 10.
iii. A computed z for X values to the left of the mean is positive.

A) (i), (ii), and (iii) are all correct statements
B) (i) is a correct statement but not (ii) or (iii).
C) (i) and (iii) are correct statements but not (ii).
D) (i) and (ii) are correct statements but not (iii).
E) (i), (ii), and (iii) are all false statements.

Question 30

Which of the following is true in a normal distribution?

A) Mean equals the mode and the median
B) Mode equals the median
C) Mean divides the distribution into two equal parts
D) Mean equals the mode and the median and Mean divides the distribution into two equal parts

Question 31

Tables of normal distribution probabilities are found in many statistics books. These probabilities are
Calculated from a normal distribution with

A) a mean of 1 and a standard deviation of 1.
B) a mean of 100 and a standard deviation of 15.
C) a mean of 0 and a standard deviation of 15.
D) a mean of 0 and a standard deviation of 1.

Question 32

The total area of a normal probability distribution is

A) between -3.0 and 3.0.
B) 1.00.
C) dependent on a value of 'z'.
D) approximated by the binomial distribution.

Question 33

Two competitive brothers, who work in two different industries, were comparing their salaries.
Because there is a difference of 4 years in their respective work experience, they decided to
Compare, not their actual salaries, but to compare their salaries against their company averages to
See who is doing better. The following gives the brothers salaries, companies mean, and standard
Deviation for each company.
Which brother earns a higher salary compared to the rest of their colleagues?

A) Tom
B) Andy
C) They both compare the same when measured against their colleagues
D) Unable to determine from the information given

Question 34

Two business major students, in two different sections of economics, were comparing test scores.
The following gives the students' scores, class mean, and standard deviation for each section.
Which student scored better compared to the rest of their section?

A) The student in section A.
B) The student in section B.
C) Both students scored the same.
D) We are unable to determine who did better from the information given.

Question 35

Two competitive brothers, who work in two different industries, were comparing their salaries.
Because there is a difference of 4 years in their respective work experience, they decided to
Compare, not their actual salaries, but to compare their salaries against their company averages to
See who is doing better. The following gives the brothers salaries, companies mean, and standard
Deviation for each company.
What is the z-score of Tom's salary?

A) -1.29
B) 1.29
C) -1.89
D) 1.89

Question 36

i. The mean of a normal distribution is represented by σ.
ii. When referring to the normal probability function, there is not just one of them; there is a "family"
Of them.
iii. Some normal probability distributions have equal arithmetic means, but their standard deviations
May be different.

A) (i), (ii), and (iii) are all correct statements.
B) (i) is a correct statement but not (ii) or (iii).
C) (i) and (iii) are correct statements but not (ii).
D) (ii) and (iii) are correct statements but not (i).
E) (i), (ii), and (iii) are all false statements.

Question 37

A random variable from an experiment where outcomes are normally distributed can have

A) any value between -∞ and +∞
B) only a few discrete values
C) a mean of 0 and a standard deviation of 1
D) no values

Question 38

Two normal distributions are compared. One has a mean of 10 and a standard deviation of 10. The
Second normal distribution has a mean of 10 and a standard deviation of 2. Which of the following is
True?

A) The locations of the distributions are different.
B) The distributions are from two different families.
C) The dispersions of the distributions are different.
D) The dispersions of the distributions are the same.

Question 39

The standard normal probability distribution is one which has:

A) a mean of 1 and any standard deviation.
B) any mean and a standard deviation of 1.
C) a mean of 0 and any standard deviation.
D) a mean of 0 and a standard deviation of 1.

Question 40

i. Asymptotic, means that the normal curve gets closer and closer to the X-axis but never actually
Touches it.
ii. When referring to the normal probability function, there is not just one of them; there is a "family"
Of them.
iii. Some normal probability distributions have different arithmetic means and different standard
Deviations.

A) (i), (ii), and (iii) are all correct statements.
B) (i) is a correct statement but not (ii) or (iii).
C) (i) and (iii) are correct statements but not (ii).
D) (ii) and (iii) are correct statements but not (i).
E) (i), (ii), and (iii) are all false statements.

Question 41

i. For a normal probability distribution, about 95 percent of the area under normal curve is within
Plus and minus two standard deviations of the mean and practically all (99.73 percent) of the area
Under the normal curve is within three standard deviations of the mean.
ii. The total area under the normal curve is 1.
iii. The mean of a normal probability distribution is 500 and the standard deviation is 10. About 68
Percent of the observations lie between 480 and 520.

A) (i), (ii), and (iii) are all correct statements.
B) (i) is a correct statement but not (ii) or (iii).
C) (i) and (iii) are correct statements but not (ii).
D) (i) and (ii) are correct statements but not (iii).
E) (i), (ii), and (iii) are all false statements.

Question 42

An accelerated life test on a large number of type-D alkaline batteries revealed that the mean life
For a particular use before they failed is 19.0 hours. The distribution of the lives approximated a
Normal distribution. The standard deviation of the distribution was 1.2 hours. About 95.44 percent of
The batteries failed between what two values?

A) 8.9 and 18.9
B) 12.2 and 14.2
C) 14.1 and 22.1
D) 16.6 and 21.4

Question 43

What is the area under the normal curve between z = 0.0 and z = 1.79?

A) 0.4633
B) 0.0367
C) 0.9599
D) 0.0401

Question 44

A sample of 500 evening students revealed that their annual incomes were normally distributed
With a mean income of $50,000 and a standard deviation of $4,000. How many students earned
Between $47,000 and $53,000?

A) 137
B) 273
C) 113
D) 387

Question 45

The mean of a normal distribution is 400 kg. The standard deviation is 10 kg. What is the area
Between 415 kg and the mean of 400 kg?

A) 0.5000
B) 0.1932
C) 0.4332
D) 0.3413

Question 46

What is the area under the normal curve between z = 0.0 and z = 2.0?

A) 1.0000
B) 0.7408
C) 0.1359
D) 0.4772

Question 47

The distribution of the annual incomes of a group of middle management employees approximated
A normal distribution with a mean of $37,200 and a standard deviation of $800. About 68 percent of
The incomes lie between what two incomes?

A) $30,000 and $40,000
B) $36,400 and $38,000
C) $34,800 and $39,600
D) $35,600 and $38,800

Question 48

What is the area under the normal curve between z = -1.0 and z = -2.0?

A) 0.0228
B) 0.3413
C) 0.1359
D) 0.4772

Question 49

A national manufacturer of unattached garages discovered that the distribution of the lengths of
Time it takes two construction workers to erect the Red Barn model is approximately normally
Distributed with a mean of 32 hours and a standard deviation of 2 hours. What percent of the
Garages take between 32 and 34 hours to erect?

A) 16.29%
B) 76.71%
C) 3.14%
D) 34.13%

Question 50

A sample of 500 evening students revealed that their annual incomes were normally distributed
With a mean income of $50,000 and a standard deviation of $4,000. How many students earned
Between $45,000 and $53,000?

A) 170
B) 273
C) 334
D) 387

Question 51

A new extended-life light bulb has an average service life of 750 hours, with a standard deviation of
50 hours. If the service life of these light bulbs approximates a normal distribution, about what
Percent of the distribution will be between 600 hours and 900 hours?

A) 95%
B) 68%
C) 34%
D) 99.7%

Question 52

The annual commissions per salesperson employed by a manufacturer of light machinery averaged
$40,000 with a standard deviation of $5,000. What percent of the sales persons earn between
$32,000 and $42,000?

A) 60.06%
B) 39.94%
C) 34.13%
D) 81.66%

Question 53

The mean amount of gasoline and services charged by Key Refining Company credit customers is
$70 per month. The distribution of amounts spent is approximately normal with a standard deviation
Of $10. What is the probability of selecting a credit card customer at random and finding the
Customer charged between $70 and $83?

A) 0.1962
B) 0.4032
C) 0.3413
D) 0.4750

Question 54

What is the proportion of the total area under the normal curve within plus and minus two standard
Deviations of the mean?

A) 68%
B) 99.7%
C) 34%
D) 95%

Question 55

The mean of a normal probability distribution is 500 and the standard deviation is 10. About 95
Percent of the observations lie between what two values?

A) 475 and 525
B) 480 and 520
C) 400 and 600
D) 350 and 650

Question 56

i. Disaster Airlines determined that the mean number of passengers per flight is 152 with a standard
Deviation of ten passengers. Practically all flights have between 142 and 162 passengers.
ii. The total area under the normal curve is less than 1.
iii. The mean of a normal probability distribution is 500 and the standard deviation is 10.
About 68 percent of the observations lie between 480 and 520.

A) (i), (ii), and (iii) are all correct statements.
B) (i) is a correct statement but not (ii) or (iii).
C) (i) and (iii) are correct statements but not (ii).
D) (i) and (ii) are correct statements but not (iii).
E) (i), (ii), and (iii) are all false statements.

Question 57

The employees of Cartwright Manufacturing are awarded efficiency ratings. The distribution of the
Ratings approximates a normal distribution. The mean is 400, the standard deviation 50. What is the
Area under the normal curve between 400 and 482?

A) 0.5000
B) 0.4495
C) 0.3413
D) 0.4750

Question 58

i. For a normal probability distribution, about 95 percent of the area under normal curve is within
Plus and minus two standard deviations of the mean and practically all (99.73 percent) of the area
Under the normal curve is within three standard deviations of the mean.
ii. The total area under the normal curve is 100%.
iii. The mean of a normal probability distribution is 500 and the standard deviation is 10.
About 95 percent of the observations lie between 480 and 520.

A) (i), (ii), and (iii) are all correct statements.
B) (i) is a correct statement but not (ii) or (iii).
C) (i) and (iii) are correct statements but not (ii).
D) (i) and (ii) are correct statements but not (iii).
E) (i), (ii), and (iii) are all false statements.

Question 59

For the normal distribution, the mean plus and minus 1.96 standard deviations will include about
What percent of the observations?

A) 50%
B) 99.7%
C) 95%
D) 68%

Question 60

The seasonal output of a new experimental strain of pepper plants was carefully weighed. The
Mean weight per plant is 15.0 pounds, and the standard deviation of the normally distributed
Weights is 1.75 pounds. Of the 200 plants in the experiment, how many produced peppers weighing
Between 13 and 16 pounds?

A) 100
B) 118
C) 197
D) 53

Question 61

The weights of cans of fruit are normally distributed with a mean of 1,000 grams and a standard
Deviation of 50 grams. What percent of the cans weigh 860 grams or less?

A) About 1%
B) About 84%
C) About 0.26%
D) About 0.01%

Question 62

A sample of 500 evening students revealed that their annual incomes were normally distributed
With a mean income of $50,000 and a standard deviation of $4,000. How many students earned
Less than $45,000?

A) 53
B) 197
C) 303
D) 35

Question 63

The average score of 100 students taking a statistics final was 70 with a standard deviation of 7.
Assuming a normal distribution, approximately how many scored 90 or higher?

A) 0.4979
B) 0.0021
C) 0.9979
D) 2.86

Question 64

The mean score of a college entrance test is 500; the standard deviation is 75. The scores are
Normally distributed. What percent of the students scored below 320?

A) About 50.82%
B) About 34.13%
C) About 7.86%
D) About 0.82%

Question 65

The average score of 100 students taking a statistics final was 70 with a standard deviation of 7.
Assuming a normal distribution, approximately how many scored less than 60?

A) 0.2271
B) 0.3729
C) 0.8929
D) D)-1.14
E) 0.0764

Question 66

The net profit from a certain investment is normally distributed with a mean of $10,000 and a
Standard deviation of $5,000. The probability that the investor will not have a net loss is:

A) 0.4772
B) 0.9544
C) 0.0228
D) 0.9772
E) 1.0

Question 67

For a standard normal distribution, what is the probability that z is greater than 1.75?

A) 0.0401
B) 0.0459
C) 0.4599
D) 0.9599

Question 68

A cola-dispensing machine is set to dispense a mean of 2.02 litres into a container labelled 2 liters.
Actual quantities dispensed vary and the amounts are normally distributed with a standard deviation
Of 0.015 litres. What is the probability a container will have less than 2 litres?

A) 0.0918
B) 0.3413
C) 0.1926
D) 0.8741

Question 69

The mean amount spent by a family of four on food per month is $500 with a standard deviation of
$75. Assuming that the food costs are normally distributed, what is the probability that a family
spends less than $410 per month?

A)0.2158
B)0.8750
C)0.0362
D)0.1151

Question 70

Suppose a tire manufacturer wants to set a mileage guarantee on its new XB 70 tire. Life test
Revealed that the mean mileage is 47,900 and the standard deviation of the normally distributed
Distribution of mileage is 2,050 miles. The manufacturer wants to set the guaranteed mileage so
That no more than 5 percent of the tires will have to be replaced. What guaranteed mileage should
The manufacturer announce?

A) 44,528
B) 32,960
C) 49,621
D) 40,922

Question 71

The average score of 100 students taking a statistics final was 70 with a standard deviation of 7.
Assuming a normal distribution, approximately how many scored greater than 65?

A) 0.2611
B) 0.2389
C) 0.7611
D) D)-0.714

Question 72

A sample of 500 evening students revealed that their annual incomes were normally distributed
With a mean income of $50,000 and a standard deviation of $4,000. What is the income that
Separates the top 5% from the lower 95% of the incomes?

A) $43,420
B) $47,320
C) $56,580
D) $52,680

Question 73

The weekly mean income of a group of executives is $1,000 and the standard deviation of this
Group is $100. The distribution is normal. What percent of the executives have an income of $925 or
Less?

A) About 15%
B) About 85%
C) About 50%
D) About 23%

Question 74

A study of a company's practice regarding the payment of invoices revealed that on the average an
Invoice was paid 20 days after it was received. The standard deviation equalled five days.
Assuming that the distribution is normal, what percent of the invoices were paid within 15 days of
Receipt?

A) 15.87%
B) 37.91%
C) 34.13%
D) 86.74%

Question 75

A sample of 500 evening students revealed that their annual incomes were normally distributed
With a mean income of $50,000 and a standard deviation of $4,000. How many students earned
More than $55,000?

A) 53
B) 197
C) 303
D) 35

Question 76

Ball-Bearings, Inc. produces ball bearings automatically on a Kronar BBX machine. For one of the
Ball bearings, the mean diameter is set at 20.00 mm (millimetres). The standard deviation of the
Production over a long period of time was computed to be 0.150 mm. What percent of the ball
Bearings will have diameters 20.27 mm or more?

A) 41.00%
B) 12.62%
C) 3.59%
D) 85.00%

Question 77

Assuming that the food costs are normally distributed, what is the probability that a family
Spends less than $410 per month?

A) 0.2158
B) 0.8750
C) 0.0362
D) 0.1151

Question 78

A sample of 500 evening students revealed that their annual incomes were normally distributed
With a mean income of $50,000 and a standard deviation of $4,000. What is the income that
Separates the top 25% from the lower 75% of the incomes?

A) $2,680
B) $47,320
C) $50,000
D) $52,680

Question 79

The driver's seat in most vehicles is set to comfortably fit a person who is at least 159 cm tall. The
Distribution of heights of adult women is approximately normal with a mean of 161.5 cm and a
Standard deviation of 6.3 cm. Determine the percentage of women who can be expected to be
Uncomfortable in the driver's seat of their car without some sort of an adjustment.

A) 0.3446.
B) 0.1554.
C) 0.6554.
D) 0.8446

Question 80

The net profit from a certain investment is normally distributed with a mean of $10,000 and a
Standard deviation of $5,000. The probability that the investor will have a net loss is:

A) 0.4772
B) 0.9544
C) 0.0228
D) 0.9772
E) 1.0