I could use some assistance with the following question:

A researcher wishes to estimate the proportion of adults who have high-speed Internet access. What size sample should be obtained if she wishes the estimate to be within 0.05 with 90% confidence if

(a) she uses a previous estimate of 0.42?

(b) she does not use any prior estimates?

(a) n= ? (round to nearest integer)

(b) n= ? (round to nearest integer)