Consider the following screening test for cancer applied to 100,000 people of whom 100 have cancer. Each test costs $6.50, picks up 75% of cancer cases., and additionally, 12% of the time, falsely diagnoses cancer. Detection of cancer (rightly or wrongly) leads to a further exact diagnostic test that costs $100. Correct early detection of cancer by the test is valued at $10,000

1. What is the marginal benefit of doing the test?
2. What are the marginal costs of doing the test?
3. Is the first test worthwhile? Why or why not?