Question

use the following results from a test for marijuana use, which is provided by a certain drug - testing company. among 144 positive test results, there are 22 false - positive results. among 151 negative results, there are 4 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 295.
b. how many subjects did not use marijuana?
a total of 169 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:

Step1: Recall probability formula

The probability formula is $P(A)=\frac{\text{Number of favorable outcomes}}{\text{Total number of outcomes}}$.

Step2: Identify values

The number of subjects who did not use marijuana is 169 (from part b), and the total number of subjects is 295 (from part a).

Step3: Calculate probability

$P=\frac{169}{295}\approx 0.573$

Answer:

0.573