Final

What is the expected value of C?

$2770

Ms. Adkins picked up 12 items in the grocery store with a mean cost of $3.25. Then she added an apple pie that costs $6.50. What is the new mean for all 13 items?

$3.50

An event A will occur with probability 0.5. An event B will occur with probability 0.6. The probability that both A and B will occur is 0.1. Which of the following is the conditional probability of A, given B?

1/6

The states differ greatly in the kinds of severe weather that afflict them. The histogram below shows the distribution of average annual property damage caused by tornadoes over the period of 50 years in the United States. Which of the following values could be the median?

12

Questions 9 and 10 refer to the following information: For children between the ages of 18 months and 29 months, there is an approximately linear relationship between height and age. The relationship can be represented by y = 64.93 + 0.63x, where y represents height (in centimeters) and x represents age (in months). Vanessa is 20 months old and is 80 centimeters tall. What is her residual?

2.47

In 1965, the mean price of a new car was $2,650 and the standard deviation was $1000. In 2011, the mean was $30,500 and the standard deviation was $9000. If a Ford Mustang cost $2300 in 1965 and $28,000 in 2011, in which year was it more expensive relative to other cars?

2011, because the standardized score is greater than in 1965

At the beginning of the school year, Mrs Mallon from Discover High School asks every student in her classes to fill out a survey that asks for their age, gender, how long they have lived at their current address, their favorite school subject, and whether they plan to go to college after high school. Which of the following best describes the variables that are being measured?

3 categorical variables. 2 quantitative (continuous) variables

An inspector examines a large shipment of several thousand laser pointers by randomly selecting and then inspecting 6 laser pointers. Suppose 1% of the laser pointers are defective. Which one of the following expressions describes the probability that exactly one of the six laser pointers is defective?

(6 / 1)(0.01)(0.99) - (0.99) is to the 5th power

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 black, and 3.5% among Asians. What is the probability that a randomly chose death was due to diabetes?

0.030

Which of the following is the probability of a "Yes" answer, given the person was Female?

0.32

Which of the following is the probability that the insurance company will have to pay at least $1000 for a randomly selected car of this model?

0.40

A cumulative relative frequency graph for the 48 races who finished the grueling 50km cross-country ski race at 2010 Vancouver Olympics is given below. Approximately what proportion of the racers finished the race in more than 2.15 hours?

0.50

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 Americans are randomly selected, what is the probability that at least 1 of them is a universal donor.

0.526

Find and interpret the standard deviation of W = the weighted average of the two measurements.

0.590. The weighted average tends to vary about 0.590 meters from its mean of 100 meters.

A special 20 sided die is constructed so that each face has one of the following numbers on it: 1,2,3, or 4. The table below gives the probability of each value (with one value missing). Which of the following is the probability of rolling an odd number?

0.6

Forrest has determined that if he gets to the bus stop at 7:30am there is a 0.15 probability that he misses the bus. If he arrives at the bus stop three consecutive days at 7:30am, what is the probability that he catches the bus all three days.

0.614

What is the probability that a randomly selected subject in the study is Male or answered "No"?

0.84

It has been estimated that about 30% of frozen chickens are contaminated with enough salmonella bacteria to cause illness if improperly cooked. Chickens are delivered to grocery stores in crates of 24. Assume the chickens are chosen for inclusion in a crate at random. The probability that a randomly selected crate has more than 4 contaminated chickens is...

0.8889

The density curve shown takes the value 0.5 on the interval 0<x<2 (it's supposed to have a line under the signs) and takes the value 0 everywhere else. What percent of the observations lie between 0.5 and 1.2?

35%

A random sample of 50 students reported their gender, then selected from 4 options of one word that best described how they felt at the time. The results are summarized in the table:

57.1%, statistic

Mrs Abbey collects health data on many women in each of several small countries. One of the variables measured for each woman in the study is her weight in pounds. The following list gives the five-number summary for the weights of adult women in one of the countries.

75%

Questions 9 and 10 refer to the following information: For children between the ages of 18 months and 29 months, there is an approximately linear relationship between height and age. The relationship can be represented by y = 64.93 + 0.63x, where y represents height (in centimeters) and x represents age (in months). Jonathon is 22.5 months old. What is his predicted height?

79.11

A track coach wants to test the effectiveness of a new training program for distance runners. He selects his two fastest runners and, using a coin flip, randomly chooses one to participate in the new program. The other will continue with the standard training regimen. He then picks the next two fastest runners and randomly assigns one to each program. He repeats the process with all his runners, choosing the two fastest remaining each time. He then compares race times within each group of runners. The study uses which of the following?

A matched pairs design

Which of the following is the best description of a simple random sample of size n from a population of size N?

A sampling method in which every group of individuals of size n is equally likely to be selected.

The owner of a chain of supermarkets notices that there is a positive correlation between the sales of root beer and the sales of ice cream over the course of the previous year. during seasons when sales of root beer were above average, sales of ice cream also tended to be above average. Likewise, during seasons when sales of root beer were below average, sales of ice cream also tended to be below average. Which of the following would be a valid conclusion from these facts?

It is likely that sales of both root beer and ice cream are confounded with another variable, such as seasonal variation in temperature.

The mosaic plot displays the distribution of emotion by gender for the random sample of 50 students. Which of the following is the best evidence that there is an association between gender and emotion?

Knowing a student's gender is helpful for predicting their current emotion.

John maintains two separate lines of lobster traps in Penobscot Bay. The East Bay trap produces a mean of 12 pounds of lobster per day with a standard deviation of 7 pounds. The West Bay trap produces a mean of 10 pounds of lobster a day with a standard deviation of 4.5 pounds. The weight of the lobsters produced by each trap is independent of the other. Which of the following are the mean and approximate standard deviation of the total weight of lobsters John traps in a day?

Mean = 22 pounds; Standard deviation = 8.32

For the density curve shown, which letters correspond to the locations of the mean and median of the distribution?

Mean = A ; Median = B

Brayden was 60% free throw shooter last season. He practiced all through the off-season and has made 12 of the first 16 free throws this season. Based on his performance and the results of this simulation, is there convincing evidence that Brayden has improved his free throw percentage? Explain.

No. The simulation shows that there is a 14% chance of doing that well or better even if he still is a 60% free throw shooter.

Which of the following is the best interpretation of the expected value E(C) that you found in question #6?

If the company insures a large number of these cars, they can expect the average cost per car to be approximately E(C).

Which of the following is true about all Normal distributions?

The area underneath the curve is equal to 1.

If a distribution is approximately symmetric, which of the following is true?

The mean and median must be approximately equal

A small company estimating its photocopying expenses finds that the mean number of copies made per day for the past 12 months is 258 copies per day with a standard deviation of 24 copies per day. Which of the following is a correct interpretation of standard deviation?

The number of copies made each day typically varies by about 24 copies from the mean.

Which of the following random variables is geometric?

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

At a carnival, a particular game requires the player to spin a wheel. When a child plays, the game operator allows them to continue to spin the wheel until they win a prize. Define X = the number of spins a child takes until they win a prize. Which, if any, of the following requirements for X to be a binomial random variable is violated in this setting?

The number of trials is fixed.

The weights of adult male Labrador Retrievers are approximately Normally distributed with a mean of 87 pounds and a standard deviation of 8 pounds. Which of the following statements is true?

The proportion of adult male Labrador Retrievers that weigh less than 80 pounds is approximately equal to the proportion that weigh more than 94 pounds.

For the track coach's study described in the previous question, which of the following best describes a conclusion that can be drawn?

We can determine whether the new training program imporves race times more than the standard program for distance runners like those in this study.

A civil engineer is testing the reliability of traffic signal controllers produced by two different companies. He has 20 sets of controllers from each company, and he has been given clearance to install the at 40 different intersections in the city. He randomly assigns the controllers from company A to 20 intersections and the controllers from company B to the other intersections. The most important reason for this random assignment is that...

randomization is a good way to create two groups of 20 intersections that are as similar as possible, so that comparisons can be made between the two groups.

Which of the following is closest to the 61st percentile of the standard Normal distribution?

z = 0.28

The two-way table below gives information on the performers in the New York Philharmonic Orchestra, categorized by section (type of instrument) and gender. You select one musician from this group at random. Which of the following statements is true about events "Plays a woodwind" and "Male"?

The events are not mutually exclusive, nor are they independent.

Other things being equal, a larger automobile engines are less fuel-efficient. You are planning an experiment to study the effect of engine size (in liters) on the fuel efficiency (in miles per gallon) of sport utility vehicles. In this study...

gas mileage is the response variable, and you expect to see a negative association

The Texas experiment described in the previous question...

has two factors: the type of AP Stats curriculum and the teacher a student is assigned to

Mrs Emerson is studying oak trees and finds that the correlation between x = the ages (measured in years) and y = height (in feet) of a sample of trees is 0.78. Which of the following statements must be true?

If we measure the height in meters instead of feet, the correlation would still be 0.78.

The Venn diagram to the right summarizes the distribution of these two events (P & I). Which one of these two way tables below conveys the same information?

Total of P=58, total of Complement of P=51

If you flip three coins, the probability of getting three heads is 0.125. Which of the following statements follows from this?

If you flip 3 coins 5000 times, the percentage of time you get three heads will be very close to 12.5%

Identify and interpret the slope of the least-squares regression line.

Slope = 0.0298. The predicted air fare increases by $0.0298 for each additional 1 mile increase in the flight distance.

A study examined the relationship between the sepal length and sepal width for two varieties of an exotic tropical plant. Varieties X and O are represented by x's and o's, respectively, in the following scatterplot:

Considering each variety separately, there is a negative correlation between sepal length and width.

A set of data describes the relationship between the size of annual salary raises and the performance ratings for employees of a certain company. The least squares regression equation is y=1400+2000x where y is the raise amount and x is the performance rating. Which of the following statements must be true?

If the mean performance rating is 1.2, then the mean raise is $3800.

Mr Beuerle asked the students in his AP Statistics class to report their overall grade point averages and their SAT Math scores. The scatterplot below provides information about his students' data. The dark line is the least squares regression line for the data, and its equation is y = 410.54 + 67.3x.

Removing this student's data point would decrease the slope of the least-squares line.

An article in the student newspaper of a large university had the headline "A's swapped for evaluations?" The article included the following...Results showed that higher grades were associated with better evaluations. Which of the following would be a valid conclusion to draw from the study?

Teachers of courses in which the mean grade is above average tend to have above-average teaching evaluations.

Which of the following best interprets s = 20.7237?

The air fare is typically about $20.7237 away fro the air fare predicted by the least-squares regression line with x = flight distance (in miles).

Here is a Normal probability plot for a set of test scores. Which statement is true for the distribution of test scores?

The distribution is skewed to the right.

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? Here is a two-way table that displays data on gender and response to this question.

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

A study of the fuel economy for various automobiles plotted the fuel consumption (in liters of gasoline used per 100 kilometers traveled) vs. speed (in kilometers per hour). A least squares line was fitted to the data. Here is the residual plot from this least-squares fit.

The residual plot clearly indicates that the relationship between speed and fuel consumption is not linear.

The pie chart describes the distribution of state tree types for the 50 states in the US. The category "Other" includes all trees that are the state tree for two or fewer states. Which of the following conclusions can we draw from this chart?

There are 10 states that have designated a pine as their state tree

We say that the design of a study is biased if...

it systematically favors certain outcomes over others.

The 16th percentile in a Normal distribution is 25 and 2.5% of the values in the distribution are greater than 40. Which of the following are the best estimates for the mean and standard deviation of the distribution?

mean = 30 ; standard deviation = 5

The mean and standard deviation of the number of contaminated chickens in a crate are...

mean = 7.2 ; standard deviation = 2.24

The distribution of the time it takes for different people to solve a certain crossword puzzle is skewed to the right, with a mean of 30 minutes and a standard deviation of 15 minutes. The distribution for z-scores for those times is:

skewed to the right, with mean 0 and standard deviation 1

An Atlanta school district wants to compare the effectiveness of a standard AP Stats curriculum and a new "hands on" AP Stats curriculum. Two experienced teachers, Mrs Davis and Mr Cohen, each teach one class with the standard curriculum and one with the new approach. Students are assigned at random to these four classes. At the end of the year, all students take the AP Stats exam. Which of the following are the experimental units in this experiment?

the students in the four classes