AP Stats Chapter 5

A survey was done in the town of Mechanicsville to estimate the proportion of cars that are red and made by companies based in Japan. A random simple of 25 cars from a student parking lot at Lee-Davis High school was taken. Which of the following statements is not correct?

A different team doing sampling independently would probably obtain a slightly different answer for their sample proportion

The Hemlock Wolly Adelgid is an insect that has accidentally been released in 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 determine 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?

All Hemlock trees in the forest from which the 200 trees were selected

Control groups are used in experiments in order to accomplish which of the following?

Limit the effects of variables other than the explanatory variable and the outcome

A materials engineer wishes to compare the durability of two different types of paving material. She has 40 different one-mile stretches of interstate highway that she's been authorized to repave for her study. She decides to carry out a matched pairs experiment. Which of the following is the best way for her to carry out the randomization for this study?

Let each of the 40 roadways act as it's own pair, dividing each roadway into the first half-mile and second half-mile. --Flip a coin for each of the 40 roadways to decide which half-mile gets which pavement

A researcher observes that, on average, the number of divorces in cities with major league baseball teams is larger than in cities without major league baseball teams. Which of the following is the most plausible explanation for this observed association?

The association is due to confounding (Major League teams tend to be in large cities with more people, hence a greater number of divorces

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 packs were randomly assigned to each of the three storage times. The treatment, experimental unit, and response are respectively:

a specific storage time, a fruit pack, amount of vitamin C

A researcher for a consumer products company is field testing a new formula for laundry detergent. He has contracted with 60 families, each with two children, who have agreed to test the product. He randomly assigns 30 families to the group that will use the new formula and 30 families to the group that will use the companies current formula. The most important reason for this random assignment is that

randomization is a good way to create two groups of 30 families that are similar as possible, so that the comparisons can be made between the two groups

Which of the following statements is true?

Non response can cause bias in in surveys because non respondents may behave differently than people who respond

You work for an advertising agency that is preparing a new television commercial to appeal to women. You have been asked to design an experiment to compare the effectiveness of three versions of the commercial. Each subject will be shown on of the three versions an then asked her attitude towards the product. You think there may be a big difference between women who are employed outside the house and those who are not. Because of these differences you should use:

a block design

We wish to draw a sample of 5 without replacement from a population of 50 households. Suppose the households are numbered 01, 02,...50, and suppose that the relevant line of the random number table 11362 35692 90842 46843 62719 64049 17823

households 11 36 23 08 42