Question 1188512
Probability nobody will test positive in a group of 17 is 0.9^17=0.1668
Probability at least one will test positive is the complement or 0.8332
Expected value for 12 groups is 0.1668*12=2.00 + 0.8332(12)=10.00
so expect 2 groups to have no positive tests and therefore 34 people have required 2 samples to be run.
The other 170 fit in the 10 tests where at least one was positive and they all had to be run separately. This is 10 tests + 170 separate=180 tests
The total expected number of tests is 182.