Many women choose to have annual mammograms to screen for breast cancer after age 40. A mammogram isn’t foolproof. Sometimes the test suggests that a woman has breast cancer when she really doesn’t (a “false positive”). Other times the test says that a woman doesn’t have breast cancer when she actually does (a “false negative”). Suppose the false negative rate for a mammogram is 0.10.

a. Explain what this probability means.

b. Which is a more serious error in this case: a false positive or a false negative? Justify your answer.