17. Use the following results from a test for marijuana use, which is provided b
ID: 3371206 • Letter: 1
Question
17. Use the following results from a test for marijuana use, which is provided by a certain drug testing company. Among 147 subjects with positive test results, there are 21 false positive results. Among 152 negative results, there are 5 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 c. What is the probability that a randomly selected subject did not use marijuana? subjects 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) We can see that 147 test results were positive, while 152 test results were negative. Hence, total number of subjects= 147+152=299
b) We assume that, positive means eating Marijuana and Negative means Not eating Marijuana. So, among 147 with test coming as eating Marijuana, 21 results were false which implies that they did not eat Marijuana. Again, among 152 with test coming as not eating Marijuana,5 were false, who ate Marijuana. Hence, total number of persons who did not eat Marijuana is=152-5+21=168
c)A randomly selecting person not using Marijuana has the probability=168/299
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