The following contingency table summarizes the number of students at a college who have a MasterCard and/or a Visa
credit card.
Have Visa
Do Not Have Visa
Total
Have MasterCard
Do Not Have
1,000
1,500
2,500
MasterCard
3,000
4,500
7,500
Total
4,000
6,000
10,000
a) Find the proportion of MasterCard holders who have Visa cards. Interpret and write this proportion as a conditional probability.
b) Find the proportion of Visa cardholders who have MasterCards. Interpret and write this proportion as a conditional probability.
c) Are the events having a MasterCard and having a Visa independent? Justify your answer.
In the July 29, 2001, issue of the Journal News (Hamilton, Ohio), Lynn Elber of the Associated Press reported that “while 40 percent of American families own a television set with a V-chip installed to block designated programs with sex and violence, only 17 percent of those parents use the device.”5
a Use the report’s results to find an estimate of the probability that a randomly selected American family has used a V-chip to block programs containing sex and violence.
b According to the report, more than 50 percent of parents have used the TV rating system (TV-14, etc.) to control their children’s TV viewing. How does this compare to the percentage using the V-chip?
[Business Statistics in Practice: Using Data, Modeling and Analytics bowerman solution]
