Chapter 5: R5.5 - Review Exercises (page 356)

2Drive to exercise : The two-way table summarizes the responses of 120 people to a survey in which they were asked, “Do you exercise for at least 30 minutes four or more times per week?” and “What kind of vehicle do you drive?”

ExerciseSedanSUVTruck
Yes251512
No202424

Suppose one person from this sample is randomly selected.

a. Find the probability that the person drives an SUV.

b. Find the probability that the person drives a sedan or exercises for at least 30 minutes four or more times per week.

c. Find the probability that the person does not drive a truck, given that she or he exercises for at least 30 minutes four or more times per week.

Short Answer

Expert verified

(a) Probability that the person drives an SUV is 0.325.

(b)The probability that the person drives a sedan or exercises for at least 30 minutes four or more times per week is 0.6.

(c)The probability that the person does not drive a truck, given that she or he exercises for at least 30 minutes four or more times per week is 0.33.

Step by step solution

01

Part (a) - Step 1 : Given Information

We are given three different vehicles and if a person exercises or not . We need to find if the person drives an SUV .

ExerciseSedanSUVTruck
Yes25
1512
No202424
02

Part (a) - Step 2 : Explanation

We need to find the total and divide favorable outcome by total outcomes in order to achieve the probability .

ExerciseSedanSUVTruckTotal
Yes2515
1252
No20242468
Total453936120

So, probability (person drives an SUV ) =39120

=0.325

03

Part (b) - Step 1 : Given Information 

We are given three different vehicles and if a person exercises or not . We need to find the probability that the person drives a sedan or exercises for at least 30 minutes four or more times per week.

04

Part (b) - Step 2 : Explanation

We need to add probability of both the cases .

Probability (person drives a sedan or exercises for at least 30 minutes four or more times per week)=Probability (person drives a sedan) +Probability (sedan in total ) -Probability (yes in exercise)

Required probability=45120+52120-25120=72120=0.6

05

Part (c) - Step 1 : Given Information 

We are given different vehicles and if a person exercises or not. We need to find the probability that the person does not drive a truck, given that she or he exercises for at least 30 minutes four or more times per week .

06

Part (c) - Step 2 : Explanation 

Required Probability=25120+15120=40120=0.33

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