A CI Is Desired for the True Average Stray-Load Loss $\mathcal { \sigma }$

question 9

Essay

A CI is desired for the true average stray-load loss μ (watts) for a certain type of induction motor when the line current is held at 10 amps for a speed of 1500 rpm. Assume that stray-load loss is normally distributed with $\mathcal { \sigma }$ = 3.0.
a. Compute a 95% CI for μ
when n = 25 and $\bar { x }$
= 60.
b. Compute a 95% CI for μ
when n = 100 and $\bar { x }$
= 60.
c. Compute a 99% CI for μ
when n = 100 and $\bar { x }$
= 60.
d. Compute an 82% CI for μ
when n = 100 and $\bar { x }$
= 60.
e. How large must n be if the width of the 99% interval for μ
is to be 1.0?