Old Multiple Choice Questions From Previous Exams*

• Men's Fitness Magazine in October, 1997 reported that the chance that a man's next meal is at McDonald's is 1 in 8. The magazine also reported that the chance was 1 in 300 that an adult man will crush a finger with a hammer over the course of a year. If you assume that the occurrence of these two events is independent you are saying:

1. That among men eating a meal at McDonald's, approximately 1 in 300 will report that they crushed a finger with a hammer in the past year

2. That eating at McDonald's is conditional on crushing a finger with a hammer

3. That it is impossible to know among adult men whether eating at McDonald's is related or not related to crushing a finger with a hammer

4. That the chance that an adult man will both eat his next meal at McDonalds and report that he crushed a finger with a hammer in the past year is slightly greater than 1 in 8

5. That men who use a hammer eat at McDonald's approximately 1 out of 8 meals

• Two UCLA students, Jamie and Rishi, are invited to a party. If the unconditional probability that Jamie wears a hat to the party is 3/5 and the unconditional probability that Rishi wears a hat to the party is 2/3

1. The chance that both do not wear hats to the party must be (1 - 3/5) + (1- 2/3) = 11/15

2. The chance that either Jamie or Rishi wear a hat to the party is 3/5 + 2/3 = 14/15

3. If you know that Jamie's and Rishi's hat wearing is mutually exclusive, the chance that both wear hats to the party is 3/5 * 2/3 = 6/15

4. If Rishi's hat wearing is independent of Jamie's, then if Jamie wears a hat, it's a safe bet that Rishi will not

5. If you assume that Jamie's choice to wear a hat does not depend at all upon Rishi's choice and Rishi's choice does not depend at all upon Jamie's choice, the chance that both wear hats to the party is 3/5 * 2/3 = 6/15

• Columnist Ann Landers was asked whether having children was worth the problems involved. She asked her readers, "If you had to do it over again would you have children"? A few weeks later her column was headlined, "Seventy Percent of Parents Say Kids Not Worth It." because 70% of the parents who wrote in said they would not have children if they could make the choice again. You read this and are most concerned about which of the following:

1. You haven't heard from people without children, so you don't know if all adults feel this way

2. There was no control group, so you don't know what would have happened if the children had not caused problems

3. The parents were not randomly assigned to conditions

4. The people who wrote in were not blind to the Lander's hypotheses and that may have resulted in generalization

5. The statistic is heavily influenced by volunteer bias and may not generalize well to the parameter value

*Correct answers are bolded.