Deck 6: The Normal Distribution, Probability, and Standard Scores

Question 1

A numerical value that describes the scores of a population is called a(n).

A)population estimate
B)population statistic
C)parameter
D)population point

Answer 1

C

Question 2

Which of the following is true of a normal distribution?

A)The distribution is symmetrical.
B)The distribution is asymptotic.
C)The distribution is continuous.
D)All the above.

Answer 2

D

Question 3

In the normal distribution, .3413 of the scores will be located in the interval between the mean and .

Answer 3

C

Question 4

In a normal distribution, what proportion of scores fall within the interval between the first standard deviation above the mean to the second standard deviation above the mean?

A).1359
B).6826
C).3413
D).8413

Question 5

The frequency distribution of a normally distributed set of scores can be described completely by the and.

A)mean, standard deviation
B)mean, median
C)median, variance
D)median, standard deviation

Question 6

Which of the following statements about a normal distribution is correct?

A)The mean usually is greater than the mode and the mode greater than the median.
B)The normal distribution is a discrete distribution.
C)The mean, median, and mode of a normal distribution are all equal.
D)The normal distribution is negatively skewed.

Question 7

Which of the following is true of a normal distribution?

A)It is a theoretical relative frequency distribution.
B)No actual set of scores is exactly normally distributed.
C)The total area under the distribution is equal to 1.0.
D)All the above.

Question 8

In a normal distribution, .9544 of the scores will be located in the interval between.

Question 9

In a normal distribution, what proportion of scores fall within the interval between the mean to one standard deviation above the mean?

A).1359
B).3413
C).6826
D).8413

Question 10

In a normal distribution, what proportion of scores fall within the interval between the mean to one standard deviation below the mean?

A).1359
B).3413
C).6826
D).8413

Question 11

The symbol σ represents the.

A)mean of a sample
B)mean of a population
C)standard deviation of a sample
D)standard deviation of a population

Question 12

Assume that intelligence test scores are approximately normally distributed with a mean of 100 and a standard deviation of 16. Thus, about percent of the people have IQ scores.

A)50; between 100 and 116
B)50; higher than 116
C)68; between 84 and 116
D)34; lower than 100

Question 13

In a normal distribution, what proportion of scores fall within the interval between the mean and the lowest value in the distribution?

A).250
B).500
C).750
D)None of the above

Question 14

In a normal distribution, .6826 of the scores will be located in the interval between.

Question 15

In a normal distribution, what proportion of scores fall within the interval between the mean and the highest value in the distribution?

A).250
B).500
C).750
D)Cannot determine from the

Question 16

The area under the normal distribution is equal to.

A)1.0
B)10
C)100
D)various values, depending on the shape of the distribution

Question 17

The cumulative relative frequency in a normal distribution is equal to.

A)zero
B)-1.0 to +1.0
C)1.0
D)100

Question 18

In a normal distribution, what proportion of scores fall within the interval between the first standard deviation below the mean to the second standard deviation below the mean?

A).6826
B).3413
C).8413
D).1359

Question 19

The symbol μ represents the.

A)mean of a sample
B)mean of a population
C)standard deviation of a sample
D)standard deviation of a population

Question 20

The normal distribution.

A)is a theoretical distribution
B)can be described completely by knowing its mean and standard deviation
C)is symmetrical and asymptotic
D)all the above

Question 21

The standard normal distribution is symmetrical about.

A)its standard deviation
B)its variance
C)the score that corresponds to z = 0.0
D)the value that corresponds to z = + or -1.0

Question 22

For a z score of +2.0 from a normal distribution with μ = 50 and σ = 10, the original score was.

A)50
B)60
C)70
D)cannot be determined from the

Question 23

If a distribution is normal with μ = 75 and σ = 15, then what proportion of the scores will fall between 60 and 90?

A).1359
B).6826
C).3413
D).9544

Question 24

A score from a normal distribution may be converted to a score on the standard normal distribution by.

Question 25

A set of normally distributed scores has a mean equal to 75 with a standard deviation equal to 25. If a score equals 100, then zobs for this score is.

A)+1.0
B)+2.0
C)+3.0
D)cannot determine without knowing sample size

Question 26

A population of scores is normally distributed with a mean of 100 and a standard deviation of 20. Approximately percent of the scores fall in the interval between 100 and 140.

A)48
B)34
C)68
D)84

Question 27

A population of scores is normally distributed with a mean of 100 and a standard deviation of 20. Approximately percent of the scores fall in the interval between 60 and 100.

A)14
B)34
C)68
D)48

Question 28

If a distribution is normal with μ = 75 and σ = 15, then what proportion of the scores will fall between 30 and 120?

A).3413
B).6826
C).9544
D).9974

Question 29

A population of scores is normally distributed with a mean of 100 and a standard deviation of 20. Approximately percent of the scores fall in the interval between 100 and 120.

A)14
B)34
C)68
D)84

Question 30

In computing zobs, the difference between an individual's score and the population mean is the population standard deviation.

A)added to
B)subtracted from
C)multiplied by
D)divided by

Question 31

If a distribution is normal with μ = 75 and σ = 15, then what proportion of the scores will fall between 45 and 105?

A).3413
B).6826
C).9544
D).9974

Question 32

If a distribution is normal with μ = 50 and σ = 10, then what proportion of the scores will fall between 30 and 70?

A).9544
B).3413
C).6826
D).9974

Question 33

Given a normal distribution with a mean of 20 and a standard deviation of 4, which of the following statements is correct?

A)More scores are above 20 than below 20.
B)More scores are above 24 than below 16.
C)There are more scores of 16 than of 18.
D)There are as many scores below 16 as there are scores above 24.

Question 34

If a distribution is normal with μ = 50 and σ = 10, then what proportion of the scores will fall between 20 and 80?

A).3413
B).6826
C).9544
D).9974

Question 35

If a distribution is normal with μ = 50 and σ = 10, then what proportion of the scores will fall between 40 and 60?

A).1359
B).3413
C).6826
D).9544

Question 36

The standard normal deviate (z) is defined as.

A)the individual score minus the population mean, divided by the population standard deviation
B)the individual score plus the population mean, multiplied by 100
C)the individual score divided by the population mean, multiplied by 100
D)none of the above

Question 37

The standard normal distribution has a mean equal to and a standard deviation equal to.

A)50; 10
B)100; 15
C)0; 1
D)1; 0

Question 38

A population of scores is normally distributed with a mean of 100 and a standard deviation of 20. Approximately percent of the scores fall in the interval between 80 and 100.

A)14
B)34
C)68
D)84

Question 39

A set of normally distributed scores has a mean equal to 75 with a standard deviation equal to 25. If a score equals 25, then zobs for this score is.

A)-1.0
B)-2.0
C)-3.0
D)cannot determine without knowing sample size

Question 40

A score from a normal distribution that is equal to the mean would result in a zobs of.

A)-1.0
B)0.0
C)+1.0
D)+ or - 1.0 depending on the value of s

Question 41

If A and B represent mutually exclusive outcomes from a probability distribution, then the probability of either A or B occurring is given by.

A)p(A) × p(B)
B)p(A) + p(B)
C)p(A) − p(B)
D)p(A) ÷ p(B)

Question 42

A and B are mutually exclusive outcomes in a probability distribution. The p(A) = .24 and the p(B) = .13. The p(A or B) then equals.

A).11
B).03
C).37
D)1.85

Question 43

In probability, the occurrence of a set of outcomes is called a(n).

A)frequency
B)event
C)probability
D)occurrence

Question 44

Which of the following corresponds to the statement: "The probability that X is equal to or greater than 75 and equal to or less than 95 is .47"?

Question 45

A probability obtained by measuring actual long-term occurrences of an event is called a(n) probability.

A)theoretical
B)empirical
C)normal
D)continuous

Question 46

The probability of an exact value of a score occurring in a continuous distribution is.

A)zero
B).25
C).50
D)1.00

Question 47

The area between z = -1.0 to z = -2.0 in a standard normal distribution contains approximately percent of the distribution of scores.

A)50
B)68
C)14
D)34

Question 48

Which of the following standard scores reflects the poorest relative performance on a test?

A)z = +2.34
B)z = 0.00
C)z = -1.21
D)z = -1.84

Question 49

The probability of a discrete event is defined as the number of outcomes comprising the event the total number of possible outcomes in a distribution.

A)added to
B)subtracted from
C)multiplied by
D)divided by

Question 50

For a normally distributed set of scores with, what is the probability of a score being equal to or less than 200?

A).3413
B).6826
C).5000
D).9544

Question 51

For a normally distributed set of scores with what is the probability of a score being equal to or greater than 200?

A).3413
B).5000
C).6826
D).9544

Question 52

The range of probabilities for the occurrence of an event.

A)is from -1.0 to 0.0
B)is from -1.0 to +1.0
C)is from 0.0 to +1.0
D)depends upon the type of event

Question 53

In the standard normal distribution, the area to the left of z = 0 contains percent of the distribution.

A)0
B)25
C)50
D)100

Question 54

A normally distributed set of scores has a μ = 500 and σ = 100. What proportion of scores is equal to or greater than 400?

A).1359
B).5000
C).3413
D).8413

Question 55

A normally distributed set of scores has a μ = 500 and σ = 100. What proportion of scores is equal to or less than 400?

A).1587
B).5000
C).3413
D).8413

Question 56

Each possible occurrence in a probability distribution is called a(n).

A)frequency
B)event
C)probability
D)outcome

Question 57

With a mean of 100 and a standard deviation of 10, the standard normal deviate for a score of 95 is.

A)+1.0
B)+0.5
C)-0.5
D)-1.0

Question 58

Outcomes in a probability distribution that cannot occur at the same time are called outcomes.

A)mutually exclusive
B)incompatible
C)separate
D)distinct

Question 59

A normally distributed set of scores has a μ = 500 and σ = 100. What proportion of scores is between 400 to 600?

A).1359
B).3413
C).6826
D).8413

Question 60

In the standard normal distribution, which of the following intervals between z scores contains the largest proportion of scores?

A)-1.0 to +1.0
B)0.0 to +1.0
C)+1.0 to +2.0
D)0.0 to -2.0

Question 61

For a normally distributed set of scores with, what is the probability of a score being between 60 to 140?

A).3413
B).5000
C).6826
D).9544

Question 62

You receive a score of 80 on a psychology test that has a mean of 71 and a sample variance equal to 9. Your standard score on the test is equal to.

A)+1.0
B)+2.0
C)+3.0
D)+4.0

Question 63

Which of the following standard scores reflects the best relative performance on a test?

A)z = -2.45
B)z = +1.10
C)z = -1.10
D)z = 0.00

Question 64

If you obtained a standard score on a history test expressed as z = 0.0 and a standard score on a mathematics test of z = -0.5, then you did.

A)relatively better on the math test
B)relatively better on the history test
C)better than average on both tests
D)worse than average on both tests

Question 65

You receive a score of 88 on a statistics examination that has a mean of 76 and a sample standard deviation equal to 8. Your standard score on the test is equal to.

A)+0.0
B)+1.5
C)+1.0
D)-1.5

Question 66

A raw score from a sample may be converted to a standard score by.

Question 67

For a normally distributed set of scores with, what is the probability of a score being between 180 to 220?

A).3413
B).5000
C).6826
D).9544