Chapter 6, Problem 14SE

IQs Wechsler IQs are approximately Normally distributed with a mean of 100 and a standard deviation of 15. Use the probabilities shown in the figure in Exercise 6.13 to answer the following questions. Do not use the Normal table or technology. You may want to label the figure with Empirical Rule probabilities to help you think about this question.

a. Roughly what percentage of people have IQs more than 100?

$\text{i}\text{. almost all ii}\text{. }95\% \text{ iii}\text{. }68\%\text{ iv}\text{. }50\%$

b. Roughly what percentage of people have IQs between 100 and 115?

$\text{i}\text{. }34\% \text{ ii}\text{. }17\% \text{ iii}\text{. }2.5\% \text{ iv}\text{. }50\%$

c. Roughly what percentage of people have IQs below 55?

$\text{i}\text{. most all ii}\text{. }50\% \text{ iii}\text{. }34\% \text{ iv}\text{. about }0\%$

d. Roughly what percentage of people have IQs between 70 and 130?

$\text{i}\text{. almost all ii}\text{. }95\% \text{ iii}\text{. }68\% \text{ iv}\text{. }50\%$

e. Roughly what percentage of people have IQs above 130?

$\text{i}\text{. }34\% \text{ ii}\text{. 17\% iii}\text{. }2.5\%\text{ iv}\text{. }50\%$

f. Roughly what percentage people have IQs above 145?

$\text{i}\text{. almost all ii}\text{. }50\% \text{ iii}\text{. }34\% \text{ iv}\text{. about }0\%$