Question 1

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

Accepted Answer

A)  Symmetry 
B)  The total area under the curve is always equal to 1. 
C)  99.72% of the time the random variable assumes a value within plus or minus 1 standard deviation of its mean. 
D)  The mean is equal to the median, which is also equal to the mode. 
A)  Symmetry 
B)  The total area under the curve is always equal to 1. 
C)  99.72% of the time the random variable assumes a value within plus or minus 1 standard deviation of its mean. 
D)  The mean is equal to the median, which is also equal to the mode.

Question 2

The assembly time for a product is uniformly distributed between 2to 10 minutes. The probability of assembling the product between 7 to 9 minutes is

Accepted Answer

A)  0. 
B)  0.50. 
C)  0.2. 
D)  0.25. 
A)  0. 
B)  0.50. 
C)  0.2. 
D)  0.25.

Question 3

When a continuous probability distribution is used to approximate a discrete probability distribution, a value of 0.5 is added to and/or subtracted from the

Accepted Answer

A)  area. 
B)  value of x. 
C)  value of z. 
D)  value of µ. 
A)  area. 
B)  value of x. 
C)  value of z. 
D)  value of µ.

Question 4

x is a normally distributed random variable with a mean of 24 and a standard deviation of 6. The probability that x is less than 11.5 is

Accepted Answer

A)  0.0186. 
B)  0.9814. 
C)  0.0076. 
D)  0.9924. 
A)  0.0186. 
B)  0.9814. 
C)  0.0076. 
D)  0.9924.

Question 5

In a normal distribution, it is known that 27.34% of all the items are included from 100 up to the mean, and another 45.99% of all the items are included from the mean up to 145. Determine the mean and the standard deviation of the distribution.

Accepted Answer

Mean = 113

Question 6

z is a standard normal random variable. What is the value of z if the area to the right of z is 0.7444?

Accepted Answer

A)  -0.66 
B)  0.66 
C)  -1.66 
D)  1.66 
A)  -0.66 
B)  0.66 
C)  -1.66 
D)  1.66

Question 7

A negative value of z indicates that

Accepted Answer

A)  the number of standard deviations of an observation is to the right of the mean. 
B)  the number of standard deviations of an observation is to the left of the mean. 
C)  a mistake has been made in computations, since z cannot be negative. 
D)  the data has a negative mean. 
A)  the number of standard deviations of an observation is to the right of the mean. 
B)  the number of standard deviations of an observation is to the left of the mean. 
C)  a mistake has been made in computations, since z cannot be negative. 
D)  the data has a negative mean.

Question 8

The highest point of a normal curve occurs at

Accepted Answer

A)  one standard deviation to the right of the mean. 
B)  two standard deviations to the right of the mean. 
C)  approximately three standard deviations to the right of the mean. 
D)  the mean. 
A)  one standard deviation to the right of the mean. 
B)  two standard deviations to the right of the mean. 
C)  approximately three standard deviations to the right of the mean. 
D)  the mean.

Question 9

The time it takes to travel from home to the office is normally distributed with μ = 25 minutes and σ = 5 minutes. What is the probability the trip takes more than 40 minutes?​

Accepted Answer

A)  ​.0013 
B)  ​.0130 
C)  ​.9987 
D)  ​.9990 
A)  ​.0013 
B)  ​.0130 
C)  ​.9987 
D)  ​.9990

Question 10

The starting salaries of individuals with an MBA degree are normally distributed with a mean of $40,000 and a standard deviation of $5,000. What is the probability that a randomly selected individual with an MBA degree will get a starting salary of at least $47,500?

Accepted Answer

A)  0.4332 
B)  0.9332 
C)  0.0668 
D)  0.5000 
A)  0.4332 
B)  0.9332 
C)  0.0668 
D)  0.5000

Question 11

Consider a binomial probability experiment with n = 3 and p = 0.1. Then, the probability of x = 0 is

Accepted Answer

A)  0. 
B)  0.0001. 
C)  0.001. 
D)  0.729. 
A)  0. 
B)  0.0001. 
C)  0.001. 
D)  0.729.

Question 12

For a normal distribution, a positive value of z indicates that

Accepted Answer

A)  all the observations must have had positive values. 
B)  the area corresponding to the z is either positive or negative. 
C)  the sample mean is smaller than the population mean. 
D)  the sample mean is larger than the population mean. 
A)  all the observations must have had positive values. 
B)  the area corresponding to the z is either positive or negative. 
C)  the sample mean is smaller than the population mean. 
D)  the sample mean is larger than the population mean.

Question 13

Joe's Record World has two stores and sales at each store follow a normal distribution. For store 1, μ = $2,000 and σ = $200 per day; for store 2, μ = $1,900 and σ = $300 per day. Which store is more likely to have a day's sales in excess of $2200?

Accepted Answer

A)  Store 1 
B)  Store 2 
C)  Store 1 and store 2 are equally likely 
D)  More information is needed 
A)  Store 1 
B)  Store 2 
C)  Store 1 and store 2 are equally likely 
D)  More information is needed

Question 14

The probability density function for a uniform distribution ranging between 2 and 6 is

Accepted Answer

A)  4. 
B)  undefined. 
C)  any positive value. 
D)  0.25. 
A)  4. 
B)  undefined. 
C)  any positive value. 
D)  0.25.

Question 15

Given that z is a standard normal random variable, what is the probability that -2.08   z   1.46?

Accepted Answer

A)  0.9091 
B)  0.4812 
C)  0.4279 
D)  0.0533 
A)  0.9091 
B)  0.4812 
C)  0.4279 
D)  0.0533

Question 16

The uniform probability distribution is used with

Accepted Answer

A)  a continuous random variable. 
B)  a discrete random variable. 
C)  a normally distributed random variable. 
D)  any random variable, as long as it is not nominal. 
A)  a continuous random variable. 
B)  a discrete random variable. 
C)  a normally distributed random variable. 
D)  any random variable, as long as it is not nominal.

Question 17

For the standard normal probability distribution, the area to the left of the mean is

Accepted Answer

A)  -0.5. 
B)  0.5. 
C)  any value between 0 to 1. 
D)  1. 
A)  -0.5. 
B)  0.5. 
C)  any value between 0 to 1. 
D)  1.

Question 18

For any continuous random variable, the probability that the random variable takes a value less than zero

Accepted Answer

A)  is any number between zero and one. 
B)  is more than one, since it is continuous. 
C)  is a value larger than zero. 
D)  is zero. 
A)  is any number between zero and one. 
B)  is more than one, since it is continuous. 
C)  is a value larger than zero. 
D)  is zero.

Question 19

z is a standard normal random variable. The P (1.41 < z < 2.85) equals

Accepted Answer

A)  0.4978. 
B)  0.4207. 
C)  0.9185. 
D)  0.0771. 
A)  0.4978. 
B)  0.4207. 
C)  0.9185. 
D)  0.0771.

Question 20

For a standard normal distribution, the probability of obtaining a z value between -1.4 to -0.35 is

Accepted Answer

A)  0.7176. 
B)  0.2824. 
C)  0.5561. 
D)  0.4439. 
A)  0.7176. 
B)  0.2824. 
C)  0.5561. 
D)  0.4439.

Exam 6: Continuous Probability Distributions

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

The assembly time for a product is uniformly distributed between 2to 10 minutes. The probability of assembling the product between 7 to 9 minutes is

When a continuous probability distribution is used to approximate a discrete probability distribution, a value of 0.5 is added to and/or subtracted from the

x is a normally distributed random variable with a mean of 24 and a standard deviation of 6. The probability that x is less than 11.5 is

In a normal distribution, it is known that 27.34% of all the items are included from 100 up to the mean, and another 45.99% of all the items are included from the mean up to 145. Determine the mean and the standard deviation of the distribution.

z is a standard normal random variable. What is the value of z if the area to the right of z is 0.7444?

A negative value of z indicates that

The highest point of a normal curve occurs at

The time it takes to travel from home to the office is normally distributed with μ = 25 minutes and σ = 5 minutes. What is the probability the trip takes more than 40 minutes?​

The starting salaries of individuals with an MBA degree are normally distributed with a mean of $40,000 and a standard deviation of $5,000. What is the probability that a randomly selected individual with an MBA degree will get a starting salary of at least $47,500?

Consider a binomial probability experiment with n = 3 and p = 0.1. Then, the probability of x = 0 is

For a normal distribution, a positive value of z indicates that

Joe's Record World has two stores and sales at each store follow a normal distribution. For store 1, μ = $2,000 and σ = $200 per day; for store 2, μ = $1,900 and σ = $300 per day. Which store is more likely to have a day's sales in excess of $2200?

The probability density function for a uniform distribution ranging between 2 and 6 is

Given that z is a standard normal random variable, what is the probability that -2.08 z 1.46?

The uniform probability distribution is used with

For the standard normal probability distribution, the area to the left of the mean is

For any continuous random variable, the probability that the random variable takes a value less than zero

z is a standard normal random variable. The P (1.41 < z < 2.85) equals

For a standard normal distribution, the probability of obtaining a z value between -1.4 to -0.35 is

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The time it takes to travel from home to the office is normally distributed with μ = 25 minutes and σ = 5 minutes. What is the probability the trip takes more than 40 minutes?