Random samples of size 400 are taken from an infinite population whose population proportion is 0.2. The mean and standard deviation of the sample proportion are
A) 0.2 and .04.
B) 0.2 and 0.02.
C) 20 and .04.
D) 20 and 0.02.

Question

Quizplus · Accepted Answer

The mean of the sample proportion is equal to the population proportion, which is 0.2. 
The standard deviation of the sample proportion is calculated as 
sqrt((p*(1-p))/n) = sqrt((0.2*0.8)/400) = 0.02. 
Therefore, the correct choice is B.

Random Samples of Size 400 Are Taken from an Infinite