Question

For this problem, carry at least four digits after the decimal in your calculations. Answers may vary slightly due to rounding.

What percentage of your campus student body is female? Let p be the proportion of women students on your campus.

(a) If no preliminary study is made to estimate p, how large a sample is needed to be 99% sure that a point estimate p̂ will be within a distance of 0.07 from p? (Round your answer up to the nearest whole number.)
students

(b) A report indicates that approximately 55% of college students are females. Answer part (a) using this estimate for p. (Round your answer up to the nearest whole number.)
students

Answer 1

a)

When preliminary estimate for proportion is not known then p = 0.50

Sample size = 2.5758² * 0.5 * 0.5 / 0.07²

= 338.5

Sample size = 339 (Rounded up to nearest integer)

b)

Given p = 0.55

Sample size = 2.5758² * 0.55 * 0.45 / 0.07²

= 335.12

Sample size = 336 (Rounded up to nearest integer)