Unit 3

Question 1

In a normal curve, the inflection points occur at ____.

Answer 1

Μ ± 1σ

Question 2

Given below are lower and upper limits of areas of the normal curve. Choose the limits that mark off the greatest proportion of the normal curve.

Answer 2

-lσ to 1σ

Question 3

Given below are lower and upper limits of areas of the normal curve. Choose the limits that mark off the greatest proportion of the normal curve.

Answer 3

-lσ to 0

Question 4

You have just received your psychology exam grade and you did better than the mean of the exam scores. If so, the z transformed value of your grade must

Answer 4

must be greater than 0.00 and

have a percentile rank greater than 50%

Question 5

Associated with a point of inflection on a normal curve is

Answer 5

one standard deviation

Question 6

A testing service has 1000 raw scores. It wants to transform the distribution so that the mean = 10 and the standard deviation = 1. To do so, ____.

Answer 6

Do a z transformation for each raw score and add 10 to each z score. and
Divide each deviation score by the standard deviation of the raw scores. Take this result for all scores and add 10 to each one.

Question 7

Would you rather have an income (assume a normal distribution and you are greedy) ____.

Answer 7

with a z score of 1.96

Question 8

Another name for a z score is

Answer 8

standard score

Question 9

Under what circumstances would a score that is 15 points above the mean be considered to be near the center of the distribution?

Answer 9

when the population standard deviation is much larger than 15

Question 10

Approximately what percentage of scores fall between z = 1 and z = 1.5?

Answer 10

9%

Question 11

A population of scores has = 42. In this population, an X value of 40 corresponds to z = 0.50. What is the population standard deviation?

Answer 11

4

Question 12

Data Set 4-3: -2, -1, 0, 2, 6

A raw score of -2 in Data Set 4-3 has a z score of

Answer 12

-1.06

Question 13

Data Set 4-4: 2, 4, 6, 8

For the population Data Set 4-4 a raw score of 6 has a z score of

Answer 13

0.45

Question 14

Data Set 4-1: 2, 7, 3, 6, 2

For population Data Set 4-1 a raw score of 7 has a z score of

Answer 14

1.43

Question 15

Approximately what percentage of scores fall between z = 0 and z = .5?

Answer 15

19%

Question 16

A population of scores has = 20. In this population, a score of X = 80 corresponds to z = +0.25. What is the population mean?

Answer 16

75

Question 17

Data Set 4-3: -2, -1, 0, 2, 6

A raw score of 6 in the population Data Set 4-3 has a deviation score of

Answer 17

5

Question 18

For any normal distribution, what is the probability of selecting a score less than the mean?

Answer 18

50%

Question 19

Suppose that Graduate Record Examination (GRE) scores are normally distributed with a mean Μ = 500 and standard deviation σ = 100. What is the z score that corresponds to a GRE score of 600?

Answer 19

1

Question 20

Let’s assume that the scores are normally distributed on a test with a population mean of 75 and standard deviation equal to 16. What is the percentile rank of a score of 56?

Answer 20

11.7

Question 21

Suppose that Graduate Record Examination (GRE) scores are normally distributed with a mean Μ = 500 and standard deviation σ = 100. What is the z score that corresponds to a GRE score of 350?

Answer 21

-1.5

Question 22

The advantage of using z scores over using raw scores is that z scores allow you to

Answer 22

compare a score in one distribution to a score in another and
understand the relationship of a score to the mean

Question 23

A z-score of z = +3.00 indicates a location that is __________.

Answer 23

far above the mean in the extreme right-hand tail of the distribution

Question 24

The theoretical normal distribution has

Answer 24

parameters

Question 25

What two parameters of a population must be known in order to use the normal curve table?

Answer 25

mean and standard deviation

Question 26

Which of the following is a characteristic of a normal distribution?

Answer 26

symmetric, unimodal, asymptotic

Question 27

The standard normal distribution is a ____ distribution with μ = ____ and σ = ____.

Answer 27

normal, 0, 1

Question 28

The theoretical normal curve has a mean equal to __________ and a standard deviation equal to __________.

Answer 28

0, 1

Question 29

What proportion of the scores in a normal distribution fall below z = –1.32?

Answer 29

0.0934

Question 30

What proportion of a normal distribution is located in the tail beyond a z-score of z = 1.50?

Answer 30

0.0668

Question 31

For a normal distribution with mean of 75 and standard deviation of 25, the proportion of the scores between 90 and 100 is

Answer 31

.1156

Question 32

A testing bureau reports that the mean for the population of Graduate Record Exam (GRE) scores is 500 with a standard deviation of 90. The proportion of scores that lie above 650 is ____.

Answer 32

0.0475

Question 33

Scores on the Math Achievement Test form a normal distribution with a mean of = 300 and a standard deviation of = 100. What score separates the top 10% of the distribution from the rest?

Answer 33

428

Question 34

A stockbroker has kept a daily record of the value of a particular stock over the years and finds that prices of the stock form a normal distribution with a mean of $8.52 with a standard deviation of $2.38. The percentage of scores that lie between $9.00 and $10.00 is ____.

Answer 34

15.31%

Question 35

SAT scores form a normal distribution with a mean of = 500 and a standard deviation of = 100. The probability of randomly selecting an SAT score greater than 450 is __________.

Answer 35

0.6915

Question 36

A normal distribution has a mean of = 60 with = 8. What is the probability of selecting an individual with a score greater than 54?

Answer 36

0.7734

Question 37

A very bright student is described as having an IQ that is three standard deviations above the mean. If this student’s IQ is reported as a z-score, the z-score would be

Answer 37

3