The contingency table below describes 200 people who entered

The contingency table below describes 200 people who entered an electronic store, according to gender and age.

If a customer who entered the store is randomly selected for a survey, what is the probability that:

a. the customer is a male and under 30

b. the customer is either a male or under 30

c. Given that the selected customer is a female, what is the probability that she is 30 and over?

Solution

a)

P(male and under 30) = 60/200 = 0.3 [answer]

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b)

P(male or under 30) = (60 + 50 + 80) / 200 = 0.95 [answer]

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c)

P(30 and over|female) = 10/(50+10) = 0.16666667 [answer]