A researcher wishes to estimate, with 90% confidence, the population proportion of adults who say chocolate is their favorite ice cream flavor. Her estimate must be accurate within 1% of the population proportion.

(a) No preliminary estimate is available. Find the minimum sample size needed.

(b) Find the minimum sample size needed, using a prior study that found that 20% of the respondents said their favorite flavor of ice cream is chocolate.

(c) Compare the results from parts (a) and (b).

(a) What is the minimum sample size needed assuming that no prior information is available?

n=?

(Round up to the nearest whole number as needed.)