Show your work. 1. An urn contains 5 red balls and 2 green balls. Two balls are

ID: 3043824 • Letter: S

Question

Show your work.

1. An urn contains 5 red balls and 2 green balls. Two balls are drawn one after the other. What is the probability that the second ball is red?

Hunter says she is itchy. There is a test for Allergy to Cats, but this test is not always right:

For people that really do have the allergy, the test says "Yes" 80% of the time

For people that do not have the allergy, the test says "Yes" 10% of the time ("false positive")

If 1% of the population have the allergy, and Hunter's test says "Yes", what are the chances that Hunter really has the allergy?

1) P(second red) = 2C1/7C1 * 5C1/6C1 + 5C1/7C1 * 4C1/6C1 = 0.714

2) P(really has the allergy) = 0.8 * 0.01 + 0.1 * 0.01 = 0.009

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.