Suppose you are a television network executive interested in how a new pilot show, Statistics, will be received by the general U. S. television-viewing population. You hire several market research firms; each recruits a random sample of television viewers and asks them to watch the pilot of Statistics. Each firm then gathers 25 respondents and asks each of them, "On a scale of I to 10, where I means you'll never watch Statistics again, and 10 means you expect to never miss an episode of Statistics, how do you rate Statistics?"

Assume that if you asked every member of the general U. S. television-viewing population about the pilot, the mean response would be 5.0 with a standard deviation of 1.7.

Each market research firm reports the mean rating of its random sample. Assume each market research firm recruits a different sample, and that you hired exactly enough market research firms such that all possible samples of 9 U. S. television viewers were sampled and their mean ratings reported. Which of the following are true about the sampling distribution of the mean ratings reported to you by the market research firms

a. The central limit theorem does not provide justification to assume that the shape of this particular distribution of mean ratings is normal.
b. The mean of the distribution of mean ratings is 4.0.
c. The standard deviation of the distribution of mean ratings is 0.07.
d. The standard error of the mean ratings is 1.7.