Use the following results from a test for marijuana use, which is provided by a

Question

Use the following results from a test for marijuana use, which is provided by a certain drug testing company. Among 141 subjects with positive test results, there are 20

false positive results. Among 151negative results, there are 33 false negative results. Complete parts (a) through (c). (Hint: Construct a table.)

a. How many subjects were included in the study?

The total number of subjects in the study was_____

b. How many subjects did not use marijuana?

A total of ___ Subjects did not use marijuana

c. What is the probability that a randomly selected subject did not use marijuana?

The probability that a randomly selected subject did not use marijuana is_____

(Do not round until the final answer. Then round to three decimal places as needed.)

Explanation / Answer

a) Total number of subjects in study = 141 + 151 = 292

b) Number of subjects who did not use marijuana = False Positive + True negative = 20 + (151 - 33) = 138

c) P(Randomly selected subject did not use marijuana) = 138/292 = 0.473

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