People were polled on how many books they read the previous year Initial survey 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 previous year within four book with 95 confidence This 95 confidence level requires 80 subjects Round up to the nearest subject b How many subjects are needed to estimate the mean number of books read the previous year within two boo with 95 confidence This 95 confidence level requires subjects Round up to the nearest subject Partial Critical Value Table Level of Confidence 1 x 100 90 95 Area in Each Tail 0 05 0 025 0 005 2 Critical Value Zxx 2 1 645 1 96 2 575 X