AP Stats Unit 8

Joaquin believes that increasing his walking speed will increase his pulse rate. In an attempt to model this relationship, Joaquin records his pulse rate, in beats per minute (bpm), while walking at each of ten different speeds, in miles per hour (mph). A regression computer output is shown above. Provided that the assumptions for regression inference are satisfied, what can you conclude about the relationship between the walking speed and the pulse rate of Joaquin?

• Since the p-value is greater than any reasonable significance level, there is significant evidence of a linear relationship between the Joaquin’s walking speed and his pulse rate.

• Since the p-value is less than any reasonable significance level, there is insignificant evidence of a linear relationship between the Joaquin’s walking speed and his pulse rate

• Since the p-value is less than any reasonable significance level, there is significant evidence of a linear relationship between the Joaquin’s walking speed and his pulse rate.

• Since the p-value is less than any reasonable significance level, no linear relationship exists between the Joaquin’s walking speed and his pulse rate.

What are the degrees of freedom for the following χ² test?

• 6

• 2

• 5

• 12

Find the degrees of freedom.

• 4

• 5

• 6

• 7

Which test would you use to see if age is a factor choosing a person’s favorite fruit? 900 college students were surveyed and their favorite fruit recorded.

• Chi-square Goodness of Fit Test

• Correlation coefficient

• Chi-Square Test for Independence

• Chi-square test for correlation

Chi-squared tests are invalid if:

• The calculated number is really large

• One of the expected values is less than 5

• One of the observed values is less than 5

• The calculated numbers is really small

What is the

χ² _calculated value for the following situation.

• 6.65

• 6.66

• 0.00991

• 1

A psychologist studied the number of puzzles that subjects were able to solve in a five-minute period while listening to soothing music. Let X be the number of puzzles completed successfully by a randomly chosen subject. The psychologist found that X has the given probability distribution. What is the probability that a randomly chosen completes more than the expected number of puzzles in the five-minute period while listening to soothing music?

• 0.1

• 0.4

• 0.8

• 1

• Cannot be determined

A psychologist studied the number of puzzles that subjects were able to solve in a five-minute period while listening to soothing music. Let X be the number of puzzles completed successfully by a randomly chosen subject. The psychologist found that X has the given probability distribution. The standard deviation of X is 0.9. Which of the following is the best interpretation of this value?

• About 90% of the subjects solved 3 or fewer puzzles

• About 68% of subjects solved between 0.9 puzzles less and 0.9 puzzles more than mean

• The typical subject solved an average of 0.9 puzzles

• The number of puzzles solved by subjects typically differed from the mean by about 0.9 puzzles

• The number of puzzles solved by subjects typically differed from one another by 0.9 puzzles

A company sells concrete in batches of 5 cubic yards. The probability distribution of X, the number of cubic yards sold in a single order for concrete from this company, is shown in the table. The expected value of the probability distribution of X is 19.25 and the standard deviation is 5.76. There is a fixed cost to deliver the concrete. The profit Y, in dollars, for a particular order can be described by Y = 75X - 100. What is the standard deviation of Y?

• $332.00

• $432.00

• $532.00

• $1,343.75

• $1,400.00

The probability of winning a certain game is 0.5. If at least 70 percent of the games in a series of games are won, the player wins a prize. If the possible choices for n are n=10, n = 20, and n=100, which value of n should the player choose in order to maximize the probability of winning a prize?

• n = 10

• n = 20

• n = 100

• n = 10 or n = 20, the probabilities are the same

• n = 10, n = 20, or n = 100; the probabilities are the same