# Statistics exam help

Test 2

Name_____________________________

Date______________________________

1. The creation of the normal curve concept is popularly credited to

a. Blaise Pascal

b. Henry Gossett

c. Sir Bryant McKenna

d. Karl Gauss

2. The normal curve is

a. symmetrical

b. unimodal

c. asymptotic to the abscissa

d. all of these

3. A bimodal distribution may never be

a. symmetrical

b. a frequency distribution

c. normal

d. all of these

4. A normal curve always has

a. a greater frequency of scores around the center than in the tails

b. a greater frequency of scores in the tails than around the center

c. a greater frequency of scores above the mean than below the mean

d. a greater frequency of scores below the mean than above the mean

5. Under the normal curve

a. the mean lies to the right of the median

b. the mode lies to the left of the mean

c. the median lies to the left of the mode

d. none of these

6. The normal curve is

a. a frequency distribution curve

b. leptokurtic

c. platykurtic

d. skewed to the left

7. When the normal curve is plotted according to standard deviation units,

each having a value of 1.00, it is called

a. platykurtic

b. leptokurtic

c. the standard normal curve

d. the deviation curve

8. Under the normal curve, 68% of the cases must always fall

a. above the mean

b. between + 1 standard deviation units from the mean

c. between + 2 standard deviation units from the mean

d. all of these, depending on the particular shape of the curve

9. Under the normal curve, 50% of the cases must always fall

a. below the mean

b. above the mean

c. below the median

d. all of these

10. When more than 34% of the cases under the curve fall between the mean and a z score of + 1, then

a. 68% of the cases fall below the mean

b. the curve cannot be symmetrical

c. the curve cannot be normal

d. none of these

11. When the mean and median do not coincide, then

a. the curve cannot be normal

b. the curve cannot be skewed

c. the curve cannot be unimodal

d. the curve cannot be a frequency distribution curve

12. Under the normal curve the 50th percentile always falls at the

a. mean

b. median

c. mode

d. all of these

13. Under the normal curve, between the z scores of + 1 and + 2, there are

always

a. 68% of the cases

b. 95% of the cases

c. 13.50% of the cases

d. sometimes a, and sometimes b, but never c

14. Under the normal curve, the percentage of cases falling above a z score of + 3, is

a. 68%

b. 95%

c. more than 1%

d. less than 1%

15. Under the normal curve, between z scores of + 10, there are always

a. 100% of the cases

b. 95% of the cases

c. 68% of the cases

d. more than 99% but less than 100% of the cases

16. When a z score falls to the left of the mean

a. it must always be given a minus sign

b. it must always be greater than 1

c. it must always be less than 1

d. none of these, since z scores never fall to the left of the mean

17. If an IQ distribution is normal and has a mean of 100 and a standard

deviation of 15, then 68% of all those taking the test scored between IQ’s of

a. 100 and 115

b. 85 and 100

c. 92.5 and 107.5

d. 85 and 115

18. If an IQ distribution is normal and has a mean of 100 and a standard

deviation of 15, then 99% of all those taking the test scored between IQ’s of

a. 0 and 150

b. 55 and 145

c. 85 and 115

d. 92.5 and 107.5

19. Under the normal curve, when the z score is equal to + 1, then

a. the standard deviation of the distribution of raw scores must equal 15

b. the standard deviation of the distribution of raw scores must equal 10

c. the standard deviation of the distribution of raw scores must equal 0

d. none of these

20. Under the normal curve, if the mean of the distribution of raw scores is

equal to 68, then its equivalent z score is equal to

a. 10

b. 1

c. 0

d. cannot tell, since the SD is not given

21. Assume a normal distribution of height scores, with a mean of 68″ and a

standard deviation of 3″, then

a. 68% of the cases must fall between 65″ and 71″

b. 50% of the cases must fall below 68″

c. 68% of the cases must fall at exactly 68″

d. a and b, but not c

22. The larger the absolute value of the z score (regardless of its sign), then

a. the higher its equivalent raw score

b. the lower its equivalent raw score

c. the further it is from the mean

d. the closer its equivalent raw score must be to the mean

23. The z score provides direct information regarding how far a given raw score

is

a. from the mean in units of standard deviation

b. from the mean in percentage units

c. from the lowest score in percentile units

d. from the highest score in percentile units

24. On any normal distribution the 50th percentile corresponds with a z score

of

a. 0

b. 50

c. 68

d. + 1

25. Under the normal curve, if a given raw score falls at the 84th percentile,

then its equivalent z score must be equal to

a. the mean

b. 0

c. + 1

d. + 2

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