Arandom sample of medical files is used to estimate the proportion p of all people who have blood type b.

(a) if you have no preliminary estimate for p, how many medical files should you include in a random sample in order to be 85% sure that the point estimate p will be within a distance of 0.07 from p?
files

(b) answer part (a) if you use the preliminary estimate that about 13 out of 90 people have blood type b.
medical files

a) 106

b) 53

Step-by-step explanation:

Minimum required medical files can be found using the formula

n≥ p×(1-p) × where

For the case (a)

If there is no preliminary estimate for p, then it is estimated as p=0.5

corresponding z-score for two tailed 85% confidence level is 1.44

and ME is 0.07.

Putting all in the formula;

n≥ 0.5×0.5 ×  ≈ 106

For the case (b)

The only difference is p=≈0.144

n≥ 0.144×0.856 ×  ≈ 53

i do not know

Step-by-step explanation: