math
posted by apryl .
Suppose that people's heights (in centimeters) are normally distributed, with a mean of 175 and a standard deviation of 6. We find the heights of 40 people.
(a) How many would you expect to be between 169 and 181 cm tall?
(b) How many would you expect to be taller than 170 cm?

This is one of the best pages for your kind of question
http://davidmlane.com/hyperstat/z_table.html
enter 175 and 6 in the "mean" and "sd" boxes.
click on the "betwee" button and enter 169 and 181 to get a range of .682689
so the number of people out of 40 to be between 169 and 181 would be
.682689(40) or appr. 27
b) click on the "above" button and enter 170, then repeat as above 
Suppose that people's heights (in centimeters) are normally distributed, with a mean of 175 and a standard deviation of 6. We find the heights of 40 people.
(a) How many would you expect to be between 167 and 183 cm tall?
1
(b) How many would you expect to be taller than 170 cm?
2