Question

1) You take a test, and 60% pass the first time and 40% fail.. The second time around, 80% pass the test and 20% fail.. The third time, 90% pass and 10% fail.. . a. What is the probability that you fail the 1st OR the 2nd time?. b. What is the probability that you fail on the 3rd time?. c. What is the probability you fail?.

Answer 1

a) P(pass 2nd) = P(fail first) * P(pass second) = .4 * .8 = .32 or 32%

b) P(pass 3rd) = P(fail first) * P(fail second) * P(pass third) = .4 * .2 * .9 = .072 or 7.2%

c) P(fail) = .4 * .2 * .1 = .008 or 0.8%