statistics
posted by Anonymous .
(Blood Test Problem) Suppose 100 people are waiting for blood test for a kind of disease. The probability that for one person the test result is positive equals 0.1. Two test methods are as follows:
Method 1: Test one by one. Then we have to do 100 tests.
Method 2: Divide 100 people into 25 groups with 4 people in each. Then, mix 4 people’s blood and test. If the result is negative, then everyone in this group is negative. If the result is positive, then we test these 4 people one by one. Now, the number of tests becomes 1+4=5.
Question: Which method is better?

If they are both as accurate, which will involve fewer tests?