Chapter 5.3, Problem 103E

To determine

To find : Probability that neither test is positive if the athlete has used steroids

Answer to Problem 103E

c. 0.02

Explanation of Solution

Given information : Test A has probability 0.9 of being positive if steroids have been used. Test B has probability 0.8 of being positive if steroids have been used.

Let A denote the event that an athlete is given test A.

Let B denote the event that an athlete is given test B.

P(A)=0.9,P(B)=0.8

P(Aâ‹‚B' )=P(A' )P(B') (as A and B are independent)

=[1-P(A) ][1-P(B)]

=(1-0.9)(1-0.8)

=0.1(0.2)

=0.02

Option c.is correct