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

A random sample of medical files is used to estimate the proportionpof all people who have blood type B.

(a)If you have no preliminary estimate forp, how many medical files should you include in a random sample in order to be 85% sure that the point estimatepwill be within a distance of0.03fromp?

Find the critical value for 85% confidence level,z_0.85, and find the specified maximal error of estimate,E. (Round your answers to two decimal places.)

z_0.85=____________

E=_______________

Compute the sample sizenfor estimating the proportionpof all people who have bloodtype Bunder these restrictions. (Round your answer up to the nearest whole number.)

n=_________medical files

(b)Answer part (a) if you use the preliminary estimate that about10out of 90 people have blood type B. (Round your proportions to three decimal places and your sample size up to the nearest whole number.)

p=________

1p=___________

n=___________medical files