Government data show that 6% of the American population are at least 75 years of age. To test a random-digit dialing device, you use the device to call randomly chosen residential telephones in your country. Of the 150 members of the households contacted, 4% are 75 years or older.
Assume that your county's population is similar to the American population in age distribution. What are the mean and standard deviation of the proportion P^ who are at least 75 years of age in samples of 150 respondents?