AP Stat Exam

A least squares regression line was fitted to the weights (in pounds) versus age (in months) of a group of many young children. The equation of the line is y = 16.6 + 0.65T where y is the predicted weight and t is the age of the child. A 20 month old child in this group has an actual weight of 25 lb. Which of the following is the residual weight in pounds for this child?

-4.60

Suppose that 2% of a clinic's patients are known to have cancer. A blood test is developed that is positive in 98% of patients with cancer but is also positive in 3% of patients who do not have cancer. If a person who is chosen at random from the clinic's patients is given the test and it comes out positive, what is the probability that the person actually has cancer?

.4

In a certain School, 17% of the students are enrolled in a psychology course, 28% are enrolled in a foreign language course, and 32% are enrolled in either a psychology course or a foreign language course or both. What is the probability that a student chosen at random from this school will be enrolled in both of foreign language course and a psychology course?

0.13

The distribution of colors of candies in a bag is as follows. If two candies are randomly drawn from the bag with replacement, what is the probability that they are the same color?

0.22

A distribution of scores is approximately normal with a mean of 78 and a standard deviation of 8.6. Which of the following equations can be used to find the score X above which 33% of the scores fall?

0.44= x-78/ 8.6

The amount of time required for each of 100 mice navigate through a maze was recorded. The histogram below shows the distribution of times in seconds for the 100 mice. Which of the following values is closest to the standard deviation of the hundred times

10 seconds

90% of the people who have a particular disease will have a positive result on a given diagnostic test. 90% of the people who do not have the disease have a negative result on the test. If 5% of a certain population has the disease, what percent of that population would test positive for the disease?

14%

The equation of the least squares regression line for the points on the scatterplot above is y= 1.3 + 0.73x. What is the residual plot (4,7)?

2.78

Each of the faces of a fair six-sided number cube is numbered with one of the numbers one through six, with a different number appearing on each face. Two such number keeps will be tossed, in the sum of the numbers appearing on the faces that land up will be recorded. What is the probability that the sum will be 4, given that the sum is less than or equal to 6?

3/15

The dotplot below displays the total number of miles that the 28 residents of one street in a certain community travel to work in one five day work week. Which of the following is closest to the percentile rank of a resident from the street who traveled 85 miles to work that week?

70

The heights of adult women are approx normally distributed about a mean of 65 inches with a SD of 2 in. If Rachel is the 99th percentile in height for adult women, then her height in inches is closet to?

70

A candy company produces individually wrapped candies. The quality control manager for the company believes that the weight of the candies is approximately normally distributed with the mean 720 milligrams (mg). If the manager's belief is correct, which of the following intervals of weights will contain the largest proportion of the candies in the distribution of weights?

700 mg to 740 mg

A random sample of 25 households from the Mountainview school district was surveyed. In this survey, data were collected on the age of the youngest child living in each household. The histogram below displays the data collected in the survey. In which of the following intervals is the median of these data located?

8 years old to less than 10 years old

The lengths of individual shellfish in a population of 10,000 shellfish are approx. normally distributed with mean 10 centimeters and standard deviation 0.2 centimeters. Which of the following is the shortest interval that contains approx. 4,000 shellfish lengths?

9.895 cm to 10.105 cm

Which of the following can be used to show a cause and effect relationship between two variables?

A controlled experiment

A school principal wanted to investigate student opinion about the food served in the school cafeteria. The principal selected at random samples of 50 first year students, 50 second year students, 50 third year students, and 50 fourth year students to complete a questionnaire. Which of the following best describes the principal's sampling plan?

A stratified random sample

The distribution of heights of 6 year old girls is approximately normally distributed what's the mean of 46.0 inches And a standard deviation of 2.7 inches. Aliyaah is 6 years old, and her height is 0.96 standard deviation above the mean. Her friend Jayne is also 6 years old and is the 93rd percentile of the height distribution. At what percentile is Aliyaah's height, and how does her height compared to Jayne's height?

Aliyaah's height is at the 83rd percentile of the distribution, and she is shorter than Jayne.

Which of the following is a key distinction between well designed experiments and observational studies?

An experiment can show a direct cause and effect relationship, wheras an observational study cannot.

A high school physics teacher was conducting an experiment with his class on the length of time it will take a marble to roll down a sloped chute. The class ran repeated trials in order to determine the relationship between the length, in centimeters, of the sloped chute and the time, in seconds, for the marble to roll down the chute. A linear relationship was observed in the correlation coefficient was 0.964. After discussing their results, the teacher instructed the students to convert all of the length measurements to meters but leave the time in seconds. What effect will this have on the correlation of the two variables?

Because chasing from centimeters to meters does not affect the value of the correlation, the correlation will remain 0.964.

The director of a technical school was curious about whether there is a relationship between students who complete one of the school's most popular Health Sciences certificate programs and whether their students go on to complete more advanced studies in the Health Sciences within two years of completing the certificate program. She randomly selected 100 students who completed the program. Data collected on these students are shown in the table below. Which of the following statements is true for these 100 students?

Being a person who did not complete the program but completed more advanced studies is less likely than being a person who completed the program and completed more advanced studies.

Lynn is planning to fly from New York to Los Angeles and will take the airtight Airlines flight that leaves at 8 am. The website she used to make a reservation states that the probability that the flight will arrive in Los Angeles on time is 0.70. Of the following which is the most reasonable explanation for how the probability could have been estimated?

From the fact that, on all previous days this particular flight had been scheduled, it had arrived on time 70% of those days.

Which of the following statements is true for two events, each with a probability greater than 0?

If the events are mutually exclusive, they cannot be independent.

Traffic data revealed that 35% of automobiles traveling along a portion of an interstate highway were exceeding the legal speed limit. Using highway cameras and license plate registration, it was also determined that 52% of sports cars were also speeding along the same portion of the highway. What is the probability that a randomly-selected car along the same portion of the highway was a speeding sports car?

It cannot be determined from the information given.

Heights in inches for the 200 graduating seniors from Washington High School are summarized in the frequency table below. Which of the following statements about the median height is true?

It is greater than or equal to 60 inches but less than 66

From the three histograms above, which of the following correctly order the histograms from the one with the smallest portion of data above its mean to the one with the largest proportion of data above its mean?

J, L, K

Suppose that the distribution of a set of scores has a mean of 47 and a standard deviation of 14. If 4 is added to each score, what will be the mean and standard deviation of the distribution of new scores?

Mean = 51 SD= 14

To check the effect of cold temp. on the elasticity of two brands of rubber bands, one box of Brand A and one box of Brand B rubber bands are tested. Ten bands from the Brand A box are placed in a freezer for two hours and ten bands from the Brand B box are kept at room temp. The amount of stretch before breakage is measured on each rubber band, and the mean of the cold bands is compared to the mean for the others. Is this a good experimental design?

No, because temperature is confounded by brand

One hundred people were interviewed and classified according to their attitude toward small cars and their personality type. Which of the following is true?

Of the three attitude groups, the group with the neutral attitude has the highest proportion of type B personality types.

Lauren is enrolled in a very large College Calculus class. On the first exam, the class mean was 75 in the standard deviation was 10. On the second exam, the class mean was 70 and the standard deviation was 15. Lauren scored 85 on both exams. Assuming the scores on each exam were approximately normally distributed, and which exam did Lauren score better relative to the rest of the class?

She scored about equally well on both exams.

A high school statistics class wants to conduct a survey to determine what percentage of students in the school would be willing to pay a fee for participating in after-school activities. Twenty students are randomly selected from each of the freshman, sophomore, junior, and senior classes to complete the survey. This plan is an example of which type of sampling?

Stratified random

A researcher wishes to test a new drug developed to treat hypertension (high blood pressure). A group of 40 hypertensive men and 60 hypertensive women is to be used. The experimenter randomly assigns 20 of the men and 30 of the women to the placebo and assigns the rest to the treatment. The major reason for separate assignment for men and women is that?

The new drug affect men and women differently

A certain type of remote control car has a fully charged battery at the time of purchase. The distribution of running times of cars of this type, before they require recharging of the battery for the first time after its period of initial use, is approximately normal with a mean of 80 minutes and a standard deviation of 2.5 minutes. The Shaded area in the figure below represents which of the following probabilities?

The probability that the running time of a randomly-selected car up this type, before it requires recharging of the battery for the first time after its period of initial use is between 75 minutes and 82.5 minutes.

At a college the scores on the chemistry final exam are approx normally distributed, with a mean of 75 and a standard deviation of 12. The scores on the calc final are also approx normally distributed with a mean of 80 and a standard deviation of 8. A student scored 81 on the chem final and 84 on the calc final. Relative to the students in each class, in which subject did this student do better>

The student did equally well in each course

A botanist is studying the petal length measured in millimeters of two species of lilies. The boxplots above illustrate that distribution of petal lengths from two samples of equal size, one from species a and the other from species B. Based on these boxplots, which of the following is a correct conclusion about the data collected in the study?

There are more petals lengths that are less than 30 mm for species B than there are for species A.

Automobile brake pads are either metallic or nonmetallic. An experiment is to be conducted to determine whether the stopping distance is the same for both types of brake pads. In previous studies, it was determined that car size ( small, medium, large) is associated with stopping distance, but car type ( sedan, wagon, Coupe) is not associated with stopping distance. This experiment would best be done?

by blocking on car size

In a large set of data that are approx normally distributed: r is the value in the data set that has a z score of -1.00 s is the value of the first quartile, and t is the value of the 20th percentile. Which of the following is the correct order from least to greatest for the values of r, s, and t?

r,t,s