Question

10. All of the normal distributions curves on the graph below have a mean of 100. a. Which has a standard deviation of approximately 5? b. Which has a standard deviation of approximately 20? ) )

solve

Answer 1

Solution:

a) Graph A has a standard deviation of approximately 5.

Because , observe that , $\mu$ + 3$\sigma$ is approximately 115

So, 3$\sigma$ = 115 - 100 = 15

$\sigma$ = 5

b) Graph C has a standard deviation of approximately 20.

Because , observe that , $\mu$ + 3$\sigma$ is approximately 160

So, 3$\sigma$ = 160 - 100 = 60

$\sigma$ = 20