A researcher believes that 47.5% of people who grew up as the only child have an IQ score over 100. However, unknown to the researcher, this figure is actually 50%, which is the same as in the general population. To attempt to find evidence for the claim, the researcher is going to take a random sample of 400 people who grew up as the only child. Let p be the proportion of people in the sample with an IQ score above 100. Answer the following. (If necessary, consult a list of formulas.) (a) Find the mean of p X 5 ? (b) Find the standard deviation of p. (c) Compute an approximation for P (p 2 0.475), which is the probability that there will be 47.5% or more people with IQ scores over 100 in the sample. Round your answer to four decimal places