Hannah S.

asked • 10/17/17

probability how many students are male and used marijuana in the past 6 months?

I have been looking at these questions for a few hours now and I am very confused. any help would be very much appreciated :)  Even if you only help with one question that would be great too! thanks :) 
 
14. The following contingency resulted from data collected from class of 120 first-year University of Calgary students. Each student was asked their (i) gender and (ii) have they used marijuana in the past six months.
Male Female
Used marijuana 24 16
Not Used marijuana 35 45

Defining the events as:
M: a first-year student is a male
F: a first-year student is a female
Used: a first-year student has used marijuana in the past six months
NotUsed: a first-year student has not used marijuana in the past six months

From this data, re-express this contingency table converting the counts to probabilities. Use this `new' table to answers the questions below.

A)  Report the probability that a randomly chosen first-year student from this class is male and has used marijuana in the past six months.
B) Find the probability that a randomly chosen first-year student from this class is male or has used marijuana in the past six months.
C) Find the probability that a randomly chosen first-year student from this class is female and has not used marijuana in the past six months.

Walter B.

answer to part B is Prob of M + Prob Used - Prob (M and Used)
Prob Male is 59/120
Prob Used is 40/120
Prob (M and Used) is 24/120
Prob of Male or Used  = 59/120+40/120-24/120=75/120=5/8=.625
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10/17/17

2 Answers By Expert Tutors

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Andy C. answered • 10/17/17

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Walter B. answered • 10/17/17

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