In his book Ounces: Risk and Odds in Everyday Life, James Burke states that ther
ID: 3171142 • Letter: I
Question
In his book Ounces: Risk and Odds in Everyday Life, James Burke states that there is a 72% chance a polygraph test (He detector test) will catch a person who is, in fact, 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? 10 % (b) Suppose a person answers 10% of a long battery of questions with lies. What percentage of the answers will the polygraph correctly indicate are lies? % (c) Repeat pans (a) and (b) if 55% of the questions are answered truthfully and 45% are answered with lies. (a) 3 % (b) 32 % (d) Repeat parts (a) and (b) if 15% of the questions are answered truthfully and the rest are answered with truthfully and the rest are answered with lie. (a) % (b) %Explanation / Answer
ANS=
a)
90% of answers are truthful
7% of truthful answers are falsely indicated as lies
0.90 * 0.07 = 0.063
6.3% of all answers are wrongly indicated as lies
b)
10% of answers are lies
72% of lies are correctly caught as lies
0.10 * 0.72 = 0.072
7.2% of all answers are correctly indicated as lie