Cumulative Exam — Cumulative exam Answers

Residents in a city are charged for water usage every three months. The water bill is computed from a common fee, along with the amount of water the customers use. The last water bills for 40 neighborhood residents are displayed in the histogram below.

When a stone is dropped in a pond, ripples are formed and travel in concentric circles away from where the stone was dropped. The equation of the least-squares regression line is . What is the predicted area of the circle, in cm2, 4 seconds after the stone is dropped?

A line goes from (1, 0) to (5, question mark). A horizontal line is at x = 5.

A popular restaurant chain advertises that it delivers orders within 30 minutes. Suppose the average delivery time for one restaurant is 27 minutes with a standard deviation of three minutes. One particular order delivery took 35 minutes. What is the z-score for this delivery time?

Manufacturers of tires report that car tires should be able to last an average of 50,000 miles. A new tire company produces a different type of tread and tests 100 randomly selected tires. This sample of 100 tires lasted an average of 51,500 miles. Assuming the new type of tread does not improve the mileage of the tire, 200 sample means were simulated and displayed on the dotplot.Using the dotplot and the sample mean mileage, is there convincing evidence that the new type of tread improves the mileage of the tire?

An ice hockey team is considering changing their team name and mascot and would like to measure city support for the change. Which of the following methods would not provide a voluntary response sample?

The scatterplot illustrates the relationship between high school and college GPAs for a sample of students.

A city official would like to know if there is public support for increasing funding for arts programs. To collect data, the city official stands outside a concert hall after a show and surveys the first 20 people to exit about their opinion of raising funds for the arts. Which of the following best describes any bias that may arise from the results?

A township supervisor hopes to improve the current recycling program by having residents separate their recycled materials by type. For example, glass and plastic materials would be placed into separate recycling containers. To measure community support for a change to the recycling program, the supervisor visits a busy shopping area and asks randomly selected residents to respond to the following question: "Do you agree that responsible citizens would separate their recycled items by type of material?” What type of bias could be present in the survey results and what is a likely direction of the bias in estimating community support for the change to the recycling program?

The parallel histograms below display the heights of men in each of two countries.

The table shows the maze-completion times, in seconds, of two sets of mice in an experiment. Which statement is true about the variability of the group times?

Without making any calculations, which distribution of data has the largest standard deviation?

A company that manufactures golf balls produces a new type of ball that is supposed to travel significantly farther than the company’s previous golf ball. To determine this, 40 new-style golf balls and 40 original-style golf balls are randomly selected from the company’s production line on a specific day. The balls are then placed in a bag and shaken. A golf pro then selects a ball and hits it using a driver. The distance the ball travels is then measured. The bag is shaken again, and the golf pro selects another ball and hits it with the same driver. He continues this procedure until all 80 of the golf balls are hit.

Residents in a city are charged for water usage every three months. The water bill is computed from a common fee, along with the amount of water the customers use. The last water bills for 40 residents from two different neighborhoods are shown in the histograms below.Which of the following is a true statement comparing the water bills of the two neighborhoods?

Aeronautical researchers have developed three different processes to pack a parachute. They want to compare the different processes in terms of time to deploy and reliability. There are 1,200 objects that they can drop with a parachute from a plane. Using a table of random digits, the researchers will randomly place the 1,200 items into three equally sized treatment groups suitable for comparison.

A 10-item statistics quiz was given to 30 students. The table below gives the scores received along with the corresponding frequencies.

To survey clients at a massage-therapy spa, a researcher alphabetically lists all of the customers the spa had last month. The researcher sends a survey to the 13th person on the list (with the number 13 being randomly chosen), then surveys every 20th customer after that. Which sampling method was used?

Water is being poured into a large, cone-shaped cistern. The volume of water, measured in cm3, is reported at different time intervals, measured in seconds. A regression analysis was completed and is displayed in the computer output.

A website lists homes for sale in a suburban town. The site provides information including neighborhood, selling price, age of the home (in years), number of bedrooms, and whether the home has a garage. Which of the variables is a categorical variable?

A researcher is comparing three new formulas for grass killer. To conduct the experiment, the researcher purchases 30 pieces of sod from various vendors to use in the study. To create the three treatment groups, the researcher numbers the pieces of sod 1–30 and places the numbers in a hat. The researcher randomly selects 10 numbers, making sure to mix the numbers between each selection, and then repeats that process one more time to select the pieces of sod in the experiment.