A new screening test for diabetes was evaluated on a group of 800 subjects, 20 percent of whom had diabetes, to determine the accuracy of the test. Of those with diabetes, 140 were identified by the procedure as having diabetes, and 500 of the people without diabetes were identified by the test as not having diabetes.

A) You decide to do sequential testing with another test that has 90 percent sensitivity and 90 percent specificity. If you believe the negative, how many will be tested a second time with the other test? Assume 20 percent prevalence.

B) What is the net sensitivity of the two-test sequence?