1. Find a point estimate for p and also construct a 90% confidence interval for p. 2. The advertising department of a nationally circulated magazine wishes to estimate the mean age of its subscribers to within 0.5 year (i. e., the margin of error E = 5) with 99% confidence. If they estimate that the standard deviation of the ages of their subscribers is about 5 years, the minimum size of the sample they must choose is closest to .