AP Statistics - Semester 1 Final

(Ch. 6) A business evaluates a proposed venture as follows. It stands to make a profit of $10,000 with a probability 3/20, to make a profit of $5000 with probability 9/20, to break even with probability 5/20, and to lose $5000 with probability 3/20. The expected profit in dollars is

A. 3000

(Ch. 5) (Goes with two-way table) You randomly select one truck owner. What is the probability that he owns a Dodge or has four wheel drive?

A. 90/125

(Ch. 1) A small company that prints custom t-shirts has 6 employees, one of whom is the owner and manager. Suppose the owner makes $120,000 per year and the other employees make between $40,000 and $50,000 per year. One day, the owner decides to give himself a $30,000 raise. Which of the following describes how the company's mean and median salaries would change?

A. The mean would increase by $5,000 and the median would not change.

(Ch. 6) Let the random variable X represent the amount of money Dan makes doing lawn care in a randomly selected week in the summer. Assume that X is Normal with mean $240 and standard deviation $60. The probability is approximately 0.6 that, in a randomly selected week, Dan will make less than

B. $255

(Ch. 2) The area under the standard Normal curve corresponding to -0.3 < Z < 1.6 is

B. 0.5631

(Ch. 1) Here are the test scores of 10 randomly chosen sixth-grade student: 145 139 126 122 125 130 96 110 118 118 To make a stemplot of these scores, you would use as stems

B. 09, 10, 11, 12, 13, 14

(Ch. 2) The mean age (at inauguration) of all US Presidents is approximately Normally distributed with a mean of 54.6. Barack Obama was 47 when he was inaugurated, which is the 11th percentile of the distribution. Which of the following is closest to the standard deviation of presidents' ages?

B. 6.18

(Ch. 2) If a store runs out of advertised material during a sale, customers become upset, and the store loses not only the sale but also goodwill. From the past experience, a music store finds that the mean number of CDs sold in a sale is 845, the standard deviation is 15, and a histogram of the demand is approximately Normal. The manager is willing to accept a 2.5% chance that a CD will be sold out. About how many CDs should the manager order for an upcoming sale?

B. 875

(Ch. 2) Which of these variables is least likely to have a Normal distribution?

B. Annual income for all 150 employees at a local high school.

(Ch. 5) Event A occurs with probability 0.2. Event B occurs with probability 0.8. If A and B are disjoint (mutually exclusive), then

B. P(A or B) = 1.0

(Ch. 4) To test the effect of music on productivity, a group of assembly line workers are given portable mp3 players to play whatever music they choose while working for one month. For another month, they work without music. The order of the two treatments for each worker is determined randomly. This is

B. a matched pairs experiment

(Ch. 6) The mean and standard deviation of the number of contaminated chickens in a crate are

B. m = 7.2; s = 2.24

(Ch. 6) If A = result of a single roll of a six-sided die and B = result of a single roll of an 8-sided die, then mean A = 3.5, s.d. A = 1.71, and mean B = 4.5, s.d. B = 2.29. If D = the difference B - A, then which of the following is true?

B. mean D = 2, s.d. D = sq. root of (1.71^2 + 2.29^2)

(Ch. 6) Roll one 8-sided die 10 times. The probability of getting exactly 3 sevens in those 10 rolls is given by

C. (10 / 3) * (1/8)^3 * (7/8)^7

(Ch. 2) A fire department in a rural county reports that its response time to fires is approximately Normally distributed with a mean of 22 minutes and a standard deviation of 11.9 minutes. Approximately what proportion of their response times is over 30 minutes?

C. 0.25

(Ch. 5) If PA = 0.24 and PB = 0.52 and A and B are independent, what is P(A or B)?

C. 0.6352

(Ch. 1) The following is a histogram showing the actual frequency of the closing prices of a particular stock on the New York Stock Exchange over a 50-day period. The class that contains the third quartile is _____

C. 30-40

(Ch. 4) We say that the design of a study is biased if which of the following is true?

C. Certain outcomes are systematically favored.

(Ch. 1) If a distribution is skewed to the right, which of the following is true?

C. The mean must be greater than the median

(Ch. 1) When testing water for chemical impurities, results are often reported as bdl, that is, below detection limit. The Following are the measurements of the amount of lead in a series of water samples take from inner-city households 5, 7, 12, bdl, 10, 8, bdl, 20, 6 Which of the following statements can we be sure is true?

C. The median lead level in the water is 7 ppm.

(Ch. 1) A sample of 250 high school students were asked, "If you had $1000 to contribute to one kind of charitable organization, which type of organization would you choose?" Below is a two-way table of responses to this question and gender. Which of the following conclusions seems to be supported by the data?

C. The proportion of males who said they would contribute to an environmental organization was higher than the proportion of females who said they would contribute such an organization.

(Ch. 4) Which of the following is a method for improving the accuracy of a sample?

C. Use large sample sizes.

(Ch. 2) If your score on a test is at the 60th percentile, you know that your score lies

C. between the median and the third quartile.

(Ch. 4) A new headache remedy was given to a group of 25 subjects who had headaches. Four hours after taking the new remedy, 20 of the subjects reported that their headaches had disappeared. From this information you conclude

C. nothing, because there is no control group for comparison

(Ch. 5) People with type O-negative blood are universal donors. That is, any patient can receive a transfusion of O-negative blood. Only 7.2% of the American population has O-negative blood. If 10 people appear at random to give blood, what is the probability that at least 1 of them is a universal donor?

D. 0.526

(Ch. 3) In the course described above, Bill scored a 90 on the first test and a 93 on the final exam. What is the value of his residual?

D. 2.0

(Ch. 5) (Goes with two-way table) You randomly select one truck owner. What is the probability that he owns a Chevy, given that he has four-wheel drive?

D. 32/80

(Ch. 2) The heights of American men aged 18 to 24 are approximately Normally distributed with a mean of 68 inches and a standard deviation of 2.5 inches. Only about 5% of young men have heights outside the range

D. 63 inches to 73 inches

(Ch. 3) In a statistics course, a linear regression equation was computed to predict the final-exam score from the score on the first test. The equation was where y is the final-exam score and x is the score on the first test. Carla scored a 95 on the first test. What is the predicted value of her score on the final exam?

D. 95.5

(Ch. 4) A nutritionist wants to study the effect of storage time (6, 12, and 18 months) on the amount of vitamin C present in freeze dried fruit when stored for these lengths of time. Six fruit packs were randomly assigned to each of the three storage times. The treatment, experimental unit, and response are respectively

D. A specific storage time, a fruit pack, amount of vitamin C

(Ch. 1) The heights of the male and female students in a class are summarized in the following boxplots. Which of the following conclusions can be drawn from this graph?

D. About 25% of the male students are taller than the tallest female student.

(Ch. 1) The mean birth weight of infants born at a certain hospital in the month of April was 128 oz. with a standard deviation of 10.2 oz. Which of the following is a correct interpretation of standard deviation?

D. The distance between the weight of each infant born in April and the mean weight was, on average, about 10.2 oz.

(Ch. 6) Which of the following random variables is geometric?

D. The number of digits I will read beginning at a randomly selected starting point in a table of random digits until I find a 7.

(Ch. 4) A survey is to be administered to recent graduates of a certain nursing school in order to compare the starting salaries of women and men. For a random sample of graduates, three variables are to be recorded: sex, starting salary, and area of specialization. Which of the following best describes a conclusion that can be drawn from this study?

D. Whether there is an association between sex and starting salary among graduates of this nursing school.

(Ch. 3) On May 11, 50 randomly selected subjects had their systolic blood pressure (SBP) recorded twice- the first time at about 9:00AM and the second time at about 2:00PM. If one were to examine the relationship between the morning and afternoon readings, then one might expect the correlation to be

D. high and positive, as those with relatively high readings in the morning will tend to have relatively high readings in the afternoon.

(Ch. 5) Of people who died in the United States in a recent year, 86% were white, 12% were black, and 2% were Asian. Diabetes caused 2.8% of deaths among whites, 4.4% among blacks, and 3.5% among Asians. The probability that a randomly chosen death was due to diabetes is about

E. 0.030

(Ch. 6) The probability that certain crate has more than 4 contaminated chickens is

E. 0.8889

(Ch. 4) The Hemlock Woolly Adelgid is an insect that has accidentally been released in the Eastern US forests from Asia. Since it has no natural enemies in the US, it is spreading rapidly. A forester studying the abundance of the insect in southern Vermont wants to deterine if it has spread that far north. He randomly selects 200 hemlock trees in a large Vermont forest and finds that 46 of them show signs of damage from this insect. To which of the following groups of trees would it be appropriate to generalize the results of the study?

E. All hemlock trees in the forest from which the 200 trees were selected.

(Ch. 5) (Goes with two-way table) You randomly select one truck owner. Which of the following is true about the events "Owner has a Chevy" and "Owner's truck has four-wheel drive"?

E. These two events are not mutually exclusive, but they are independent.