Question

In Exercises 23-26, use these results from the I-Panel-THC .est for marijuana use, which is provided by the company Drug test Sucess: Among 143 subjects with positive test results, there are 24 false positive results 157 negative results, there are 3 false negative reslts( Hint: Construct a table similar to table 4-1, which is included with the chapter problem.

23. screening for marijuana. Use If 2 of the subjects are randomly selected without replaement. what is the probaility tha they both had correct test results(either true positive or true negative)? Is such an event unlikely

24.Screening for mariguana . Use If 2 of the subjets are randomly selected without replacement. What is the probability that they both had incorrect test results (either false positive or false negative)? Is such an event unlikely

25. Screening for marijuana. Use If 3 the subjects ae randomly selected without replacement, What is the probability that they all had false positive test results? Is such an event unlikely.

Answer 1

	use	do not use	total
+ve	119	24	143
-ve	3	154	157
total	122	178	300

23)

probability that they both had correct test results =(273/300)*(272/299)=0.8278

since above probability is higher than 0.05 ,above is not an unlikely likely

24)

P(both incorrect result) =(27/300)*(26/299)=0.0078

since above probability is lower than 0.05 ,above is an unlikely likely

25)

probability that they all had false positive test results =(24/300)*(23/299)=0.0062

since above probability is lower than 0.05 ,above is an unlikely likely