AP Stats Chapter 11

To answer the question posed above about car color and speeding tickets, the appropriate null hypothesis is:

• The observed counts are all equal to 30.

• The observed number of speeding tickets is the same for all four color groups.

• At least one of the four car color percentages is different from the other three.

• The distribution of car colors for the speeding citations is the same as the distribution of colors for cars on the highway.

• The observed counts are equal to the expected counts.

Which of the following are the correct expected counts for speeding tickets under the null hypothesis?

• 
• 
• 
• 
• 

• 3

• 4

• 7

• 999

• 1000

• 
• 
• 
• 
• 

• greater than 0.20.

• between 0.10 and 0.20.

• between 0.05 and 0.10.

• between 0.01 and 0.05.

• less than 0.01.

Which of the following statements is true of chi-square distributions?

• As the number of degrees of freedom increases, their density curves look less and less like a normal curve.

• As the number of degrees of freedom increases, their density curves look more and more like a uniform distribution.

• Their density curves are skewed to the left.

• They take on only positive values.

• All of these are true.

Which of the following is a condition that must be satisfied to use a chi-square goodness-of-fit test?

• The expected count for each category is greater than 5.

• The sample size is greater than 30.

• The expected count is the same for each category.

• The number of categories is small relative to the number of observations.

• The population distribution is approximately Normal.

• The distribution of grades in all introductory statistics courses must be approximately Normal.

• The number of categories is small relative to the number of observations.

• All the observed counts are greater than 5.

• Each observation was randomly selected from the population of all grades given by the new teacher.

• All expected counts are approximately equal.

• A

• B

• C

• D

• F