People were golled on how many books they read the peevious yoar. Initial suryey resuits indicale that s = 15.5 books. Comclete parts (a) through (d) below. Click the son to view a parkal table of eriscal values. (a) How many wubjects are needed to estimate the mean number of books tead the previous year within four bocks wit 95% confidence? This 95% conidence level requires subjects. (Round up to the nearest subject.) (b) How many subjects are needed io estimate the mean number of books read the previcus yoar within two books with 96% connisence? This 96% confidence levvol roquires subjocts. (Round up to the rioarest subjoct.)