Question

In his book Chances: Risk and Odds in Everyday Life, James Burke states that there is a 72% chance a polygraph test (lie detector test) will catch a person who is, in fact, lying. Furthermore, there is approximately a 7% chance that the polygraph will falsely accuse someone of lying. (Round your answers to one decimal place.) (a) Suppose a person answers 90% of a long battery of questions truthfully. What percentage of the answers will the polygraph wrongly indicate are lies

Answer 1

6.3%

Explanation:

From the informationn we have available in this question, there is 7% chance that this polygraph would accuse someone falsely and a 72% chance that the polygraph would be correct in predicting a list.

Now if a person's answer is 90% correct,

The percentage that the polygraph would pick wrongly to be lies =

0.07 x 0.90 x 100

= 6.3%