Topic 2 Tutorial Questions

Question 3

An advertising executive is studying television viewing habits of married men and women during prime time hours. On the basis of past viewing records, the executive has determined that during prime time, husbands are watching television 60% of the time. It has also been determined that when the husband is watching television, 40% of the time the wife is also watching. When the husband is not watching television, 30% of the time the wife is watching television.

1. Find the probability that both the wife and the husband are watching television in prime time.

2. Find the probability that the wife is watching television in prime time.

Approach:

Many students have trouble completing this question because they have trouble constructing the contingency table. The difficult part in this question is identifying the two variables that make up the contingency table. Some students may think that the two variables are "Husband or Wife" and "Watching or Not Watching".

	Husband	Wife	Total
Watching
Not Watching
Total

But this actually incorrect and misleading. If we were to truly understand the question, we would come to the realization that the two variables are actually "Husband watching TV" and "Wife watching TV".

	Husband Watching	Husband Not Watching	Total
Wife Watching
Wife Not Watching
Total

Now it should become really easy to plug in the probabilities given by the question. I'll leave you to finish off the question!