A sample of 66 observations will be taken from a process (an infinite population). The population proportion equals 0.12. The probability that the sample proportion will be less than 0.1768 is
A)0.0568
B)0.0778
C)0.4222
D)0.9222

Question

Quizplus · Accepted Answer

The sample proportion follows a normal distribution with mean equal to the population proportion (0.12) and standard deviation equal to sqrt[(0.12)(0.88)/66]. Using the standard normal distribution, the probability that the sample proportion is less than 0.1768 corresponds to a z-score of approximately 1.42, which gives a cumulative probability of about 0.9222.

A Sample of 66 Observations Will Be Taken from a Process