i need help on part d

People were polled on how many books they read the previous year. Initial survey results indicate that sequals

=17.4

17.4 books. Complete parts (a) through (d) below.

(a) How many subjects are needed to estimate the mean number of books read the previous year within four

four books with 90

90% confidence?

This 90 %

90% confidence level requires

52

52 subjects. (Round up to the nearestsubject.)

(b) How many subjects are needed to estimate the mean number of books read the previous year within two

two books with 90

90% confidence?

This 90 %

90% confidence level requires

205

205 subjects. (Round up to the nearestsubject.)

(c) What effect does doubling the required accuracy have on the samplesize?

A.

Doubling the required accuracy nearly quarters the sample size.

B.

Doubling the required accuracy nearly quadruples the sample size.

Your answer is correct.

C.

Doubling the required accuracy nearly doubles the sample size.

D.

Doubling the required accuracy nearly halves the sample size.

(d) How many subjects are needed to estimate the mean number of books read the previous year within four

four books with 99

99% confidence?

This 99

99% confidence level requires

nothing

subjects. (Round up to the nearestsubject.)