A Manufacturer of Cream Filled Donuts Wants to Make Sure

Multiple Choice

A manufacturer of cream filled donuts wants to make sure that its automatic filling process is on target. Based on a sample of 25 donuts the mean weight of cream filling is
Estimated to be 15 grams with a standard deviation of 1.5 grams. However, the quality
Control inspectors wish to estimate the mean weight of cream filling more accurately so
That they can be 99% confident that it is within 0.25 grams of the true mean. How many
Donuts should they sample?

A) 150
B) 543
C) 212
D) 410
E) 239