People were polled on how many books they read the previous year. Initial survey results indicate that s = 12.1 books. Complete parts (a) through (d) below. Click the icon to view a partial table of critical values.
(a) How many subjects are needed to estimate the mean number of books read the provious year within four books with 90% confidence?
This 90% confidence level requires subjects. (Round up to the nearest subject.)