Question

# Refer to the sample data for polygraph tests shown below. If one of the test subjects...

Refer to the sample data for polygraph tests shown below. If one of the test subjects is randomly​ selected, what is the probability that the subject is not​ lying? Is the result close to the probability of

0.449

for a negative test​ result?

No (Did Not Lie)   Yes (Lied)
Positive test results   14   40
Negative test results   33   11

The probability that a randomly selected polygraph test subject was not lying is

nothing.

​(Type an integer or decimal rounded to three decimal places as​ needed.)

Is the result close to the​ probability, rounded to three decimal​ places, of

0.449

for a negative test​ result?

No,

Yes,

because there is

more than

less than

exactly

a 0.050 absolute difference between the probability of a true response and the probability of a negative test result.

Solution:

No (Did Not Lie)   Yes (Lied) total
Positive test results   14   40 54
Negative test results   33   11 44

total 47 51 98

L as the randomly selected polygraph test subject was not lying, the event N as the randomly selected test is negative test.

The total number of possible ways is 98

N(S) =98

number of possible ways that a randomly selected polygraph test subject was not lying is = 14 +33 = 47

The required probability is, N(L) / N(S) = 47/98 = 0.479

The number of possible ways that a randomly selected test is negative test is,

N(N)= 33 + 11 =44

The required probability

P(N) = 44/98 =0.4489

Yes, because there is less than a 0.050 absolute difference between the probability of a true response and the probability of a negative test result.

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