Catherine Chao,Director of Marketing Research,needs a sample of Kansas City households to participate in the testing of a new toothpaste package. If 40% of the households in Kansas City prefer the new package,the probability that Catherine's random sample of 300 households will have a sample proportion between 0.35 and 0.45 is ___________.
A) 0.9232
B) 0.0768
C) 0.4616
D) 0.0384
E) 0.8976

Question

Quizplus · Accepted Answer

The sample proportion follows a normal distribution with mean 0.40 and standard deviation sqrt[(0.40)(0.60)/300]. Using the standard normal distribution, the probability that the sample proportion is between 0.35 and 0.45 is approximately 0.9232.

Catherine Chao,Director of Marketing Research,needs a Sample of Kansas City