STATISTICS
9. Use the given information to find the minimum sample size required to estimate an unknown population proportion, p.
A recent study reported that 70% of adults go to the doctor for their yearly check up. If you want to test the validity of this claim, how many adults must be surveyed in order to be 90% confident that the sample percentage is in error by no more than five percentage points?
A. 17
B. 138
C. 228
D. 457
