AP Stat Exam
The protein content for the 15 bean varieties has a mean of 12.2 grams and a standard deviation of 5.3grams. The mean carbohydrate content is 33.6 grams with a standard deviation of 15.7 grams. The correlation is 0.84. Which of the following expressions represents the slope of the least squares regression of Y=protein content on X= Carbohydrate content?
(0.84)(5.3)/(15.7)
A efficiency consultant determines that on the assembly line at widget manufacturing, there is a strong, negative, linear relationship between x= the number of consecutive hours a worker has been assembling widgets and y= the number of widgets he can produce in an hour. He finds that 70% of the variation in widgets produced per hour can be explained by the regression of y & x. Which of the following is the best approximation of the correlation of x & y.
-0.84
A special- sided die is constructed so that each face has either a 1, 2, 3, or 4 on it. 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
Gabriel has determined that if he gets to the bus stop by 7:30 am, there is a 0.15 probability that he misses the bus. If he is at the bus stop three consecutive days at 7:30am, what is the approximate probability that he catches the bus all three days.
0.614
One flight- Philadelphia to West Palm Beach, FL- is 953 miles long and costs $110. Which of the following expressions correctly represents the residual for this data point?
110-(101.24+0.02977x953)
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?
30-40
What is the probability that he owns a chevy, given that he has four wheel drive.
32/80
The cumulative relative frequency graph at right shows the distribution of lifespans for 39 U.S. Presidents. Which of the following is closest to the 70th percentile of this distribution?
77 years
What is the probability that he owns a dodge or has four wheel drive?
90/125
The five-number summary for the weights (in grams) of 1200 tomatoes grown in a certain greenhouse was 90 113.5 140 161 236 How many tomatoes weighed less than 161 grams?
900
1200 tomatoes have a mean weight of 143 grams and a standard deviation of 35 grams. If the weights are normally distributed, approximately how many tomatoes weigh between 73 grams and 178 grams?
978
The heights (in centimeters) of the male and female students in class are summarized in the following box plots... Which of the following is conclusions can be drawn from this graph?
About 25% of the male students are taller than the tallest female student.
The media age of five people in a meeting is 30 years. One of the people -a 50 year old- leaves the room. The median age of the remaining four people in the room is?
Cannot be determined from the information given
Which of the following is NOT true about standard deviation?
If the units for the data are in inches, standard deviation is in square inches.
A forester studying oak trees 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.
If you flip three coins, the probability of getting three heads is o.125. Which of the following statements follows from this?
If you flip three coins 5000 times, the percentage of time you get three heads will be very close to 12.5%
What is the principle purpose of control in a randomized comparative experiment?
Isolating the effect of the treatment variable by keeping all other variables the same in the treatment groups.
For the data in the previous problem, which measures of center and spread would be most appropriate to use?
Median and standard deviation
Which of the following statements about standard deviation is true?
Standard deviation is always a non-negative number.
An airline has 10 daily flights from Philadelphia to Denver. To assess customer satisfaction, a random sample of 15 passengers from each flight on a single day are asked to fill out a survey about their experience on the flight. What type of sample is this?
Stratified Random Sample
Some studies of the relationship between car color and frequency of accidents have found that red cars are more likely to be in accidents than black cars, despite how visible they are. Some experts warn that we should not conclude that red cars are less safe than black cars, because of possible confounding. Which of the following best describes what this means?
Studies of this type are all observational, and it is not possible to separate the effect of car color from the type of people who choose to drive red cars.
The scatterplot at right shows the relationship between carbs and protein in one-cup servings of 15 different varieties of beans. Which of the following best describes how correlation would change if we removed navy beans from the data set?
The correlation would be closer to 1, because the remaining data would have a stronger positive relationship.
According to the U.S Bureau of Labor Statistics. the monthly percentage change in the number of jobs in a certain state for the twelve months of 2011 had a mean of 0.08% and a standard deviation of 1.70%. From this information we can conclude that
The magnitude of the monthly deviations from the mean change averaged about 1.70%
A biology teacher has just finished grading a quiz for a class of 26 students and has calculated measures of center and spread on the scores. While writing the grades on the quizzes, he realizes he made a mistake, and the highest grade should be 10 points higher. Which one of the following sets of measurements will he have to recalculate.
The mean and standard deviation
One hundred people work at Lagtime Internet Services. Suppose after a particularly successful year, the president of the company decided to double his own salary and not change anyone else's. Assuming the president makes more than anyone else, which of the following statements about changes in measures of center and spread is true?
The mean and standard deviation will increase, but the median and interquartile range will stay the same.
The time it takes people to finish a certain kind of puzzle is strongly skewed right. Which of the following statements is true about the mean and median of this distribution?
The mean will be greater that the median.
At right are box plots describing the distribution of prices paid for homes in suburbs of Columbus, Ohio over a single 30-day period in 2012. Which of the following statements is supported by the information in this graph?
The median house price in Dublin is higher than the 75th percentile of house price in westerville.
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 taken from inner-city households (in parts per million) 5, 7, 12, bdl, 10, 8, bdl, 20, 6
The median lead level in the water is 7ppm
A researcher reports that the participants in his study lost a mean of 10.4 pounds after two months on his new diet. A friend of yours comments that she tried the diet for two months and lost no weight, so clearly the report was a fraud. Which of the following statements is correct?
The report gives only the mean. This does not imply that all participants in the study lost 10.4 pounds or even that all lost weight. Your friend's experience does not necessarily contradict the study results.
Which of the following best describes what S=20.7237 measures?
The standard deviation of the residuals
At right is a stem plot of the weights of 18 adult Maine Coon Cats. Which one of the following statements must be true about this distribution?
The standard score for a 14-pound cat is negative
A recent investigation of prices for five-year-old Toyota Camrys in Montgomery, Alabama, and New York, New York, revealed that the mean price in Montgomery was $13,200 with a standard deviation of $1000. In New York, the mean price was $12,000 with a standard deviation of $1,800. Which of the following statements is true?
The standard score for a car priced $15,000 would be higher in Montgomery than in New York.
The least squares regression line minimizes which one of the following quantities?
The sum of the squared differences between the observed values of the response variable and the predicted values of the response variable.
Which one of the following is true about the events "owner has a chevy" and "owner's truck has four-wheel drive"
These two elements are not mutually exclusive, but they are independent.
At the beginning of the school year, a high-school teacher asks every student in her classes to fill out a survey that asked for their age, gender, the number of years 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.
Three categorical variables and two quantitative variables.
The customer service department of an online store keeps track of the length of time customers wait on hold for a rep. the mean wait time is 5min and the standard deviation is 2.3 minutes. Suppose the company wants to change the variable from minutes to seconds exceeding a target time of 120 seconds. That is, if X is wait time in minutes, the new variable is Y=60x-120. which of the following are the mean and standard deviation of Y?
my=180; theta "y" = 138
Below is a pie chart of how a randomly selected group of people describesd the cost of their health insurance.
question is easy, just look at graphs.
The graph below shows how mothers of young children respond to the question, "How many times a week do you choose fast food as a dining option for your family?"
using proportionally-sized hamburgers exaggerates differences between responses.
Which of the following is closest to the 61st percentile of a standard normal distribution?
z=o.28