AP Statistics Unit 8

The National Longitudinal Study of Adolescent Health interviewed a random sample of 4877 teens (grades 7 to 12). One question asked was "What do you think are the chances you will be married in the next ten years?" Above is a two-way table of the responses by gender. Which of the following would be the most appropriate type of graph for these data?

• A bar chart showing the marginal distribution of opinion about marriage

• bar chart showing the marginal distribution of gender

• A bar chart showing the conditional distribution of gender for each opinion about marriage

• A bar chart showing the conditional distribution of opinion about marriage for each gender

• Dotplots that display the number in each opinion category for each gender

The National Longitudinal Study of Adolescent Health interviewed a random sample of 4877 teens (grades 7 to 12). One question asked was "What do you think are the chances you will be married in the next ten years?" Above is a two-way table of the responses by gender. For these data, χ2 = 69.8 with a P-value of approximately 0. Assuming that the researchers used a significance level of 0.05, which of the following is true?

• A type I error is possible 
  

• A type II error is possible 
  

• Both a type I and type II error are possible

• There is no chance of making a type I or type II error because the P-value is approximately 0

• There is no chance of making a type I and type II error because the calculations are correct

Recent revenue shortfalls in a Midwestern state led to a reduction in the state budget for higher education. To offset the reduction, the largest state university proposed a 25% tuition increase. It was determined that such an increase was needed simply to compensate for the lost support from the state. Separate random samples of 50 freshmen, 50 sophomores, 50 juniors, and 50 seniors from the university were asked whether or not they were strongly opposed to the increase, given that it was the minimum increase necessary to maintain the university’s budget at the current levels. The results are given in the table. Which hypotheses would be appropriate for performing a chi-square test?

• The null hypothesis is that the closer students get to graduation, the less likely they are to be opposed to tuition increases. The alternative is that how close students are to graduation makes no difference in their opinions.

• The null hypothesis is that the mean number of students who are strongly opposed is the same for each of the four years. The alternative is that the mean is different for at least two of the four years.

• The null hypothesis is that the distribution of student opinion about the proposed tuition increase is the same for each of the four years at this university. The alternative is that the distribution is different for at least two of the four years.

• The null hypothesis is that year in school and student opinion about the tuition increase in the sample are independent. The alternative is that these variables are dependent.

• The null hypothesis is that there is an association between year in school and opinion about the tuition increase at this university. The alternative hypothesis is that these variables are not associated.

Recent revenue shortfalls in a Midwestern state led to a reduction in the state budget for higher education. To offset the reduction, the largest state university proposed a 25% tuition increase. It was determined that such an increase was needed simply to compensate for the lost support from the state. Separate random samples of 50 freshmen, 50 sophomores, 50 juniors, and 50 seniors from the university were asked whether or not they were strongly opposed to the increase, given that it was the minimum increase necessary to maintain the university’s budget at the current levels. The results are given in the table. The conditions for carrying out the chi-square test is: I. Separate random samples from the populations of interest II. Expected counts large enough III. The samples themselves and the individual observations in each sample are independent. Which of the conditions is (are) satisfied in this case?

• I only

• II only

• I and II only

• II and III only

• I, II and III

Is this a probability distribution?

• No, the sum of p(x) does not equal 1.

• Yes, all p(x) are between 0 and 1.

• No, all p(x) are not between 0 and 1.

• Yes, the sum p(x) is 1.

Is this a probability distribution?

• No

• Yes

• A

• B

• C

• D

• E

A random sample of traffic tickets given to motorists in a large city is examined. The tickets are classified according to the race of the driver. The results are summarized in the table. We wish to test H0: The racial distribution of traffic tickets in the city is the same as the racial distribution of the city’s population. Assuming H0 is true, the expected number of Hispanic drivers who would receive a ticket is

• 8

• 10.36

• 11

• 11.84

• 12

A random sample of traffic tickets given to motorists in a large city is examined. The tickets are classified according to the race of the driver. The results are summarized in the table. We wish to test H0: The racial distribution of traffic tickets in the city is the same as the racial distribution of the city’s population. We compute the value of X2 to be 6.58. Assuming the conditions for inference are met, the p-value of our test is

• greater than 0.2

• between 0.10 and 0.20

• between 0.05 and 0.10

• between 0.01 and 0.05

• less than 0.01

A random sample of traffic tickets given to motorists in a large city is examined. The tickets are classified according to the race of the driver. The results are summarized in the table. We wish to test H0: The racial distribution of traffic tickets in the city is the same as the racial distribution of the city’s population. The category that contributes the largest component to the X2 statistic is

• White

• Black

• Hispanic

• Other

• The answer cannot be determined since this is only a sample