Unit Test Answers

The number of text messages that Reza sent each day so far in this billing cycle is shown on the dot plot.

To conduct a survey about the type of phone service most people in Greenville prefer, 10 different blocks in the neighborhood are chosen. On these 10 blocks, 10 houses are selected at random, and then each resident of each of those houses is interviewed. This type of sampling method is

A convenience sample differs from a voluntary sample in that

Many businesses and organizations insist that official communications use professional-looking fonts, such as Times New Roman. Fonts characterized as less professional, such as Comic Sans, should be avoided. A student would like to determine if font choice makes a difference in the average grade on a typed response in English classes. There are currently four English classes available from which the student can collect data, and each class has a similar writing assignment. The student considers two methods for collecting data.Method A: At the start of the assignment, students choose a font, either Times New Roman or Comic Sans, and then complete the assignment.Method B: At the start of the assignment, students are randomly assigned one of two fonts, either Times New Roman or Comic Sans, and then complete the assignment.In both methods, the teachers grade the papers received, and the mean grade for each font is determined.

An auto-parts store offers a fuel additive that claims to increase a vehicle’s gas mileage. The additive is poured into a vehicle’s gasoline tank after the tank is filled. To measure the claim, two methods to collect data are proposed.Method A: 20 similar police cars owned by a city are selected. After the cars are filled with a fresh tank of gasoline, researchers randomly select 10 of the cars to receive the additive, while the other 10 do not receive the additive. The gas mileage for each car is recorded in miles per gallon.Method B: 20 customers at an auto-parts store receive free coupons for the additive and are asked to use it with their next fresh tank of gasoline. The customers then report their gas mileage with the fuel additive.

Nico wanted to determine the number of students in his school who buy school lunch. He walked around the cafeteria one lunch period looking to see whether every fifth person in the cafeteria purchased lunch or brought their own.

A teacher assigns 10 questions for homework and wants to randomly pick 3 questions to be graded. Which of the following procedures would produce a simple random sample?

A college professor hypothesizes that readers will comprehend more when reading a graphic novel than when reading text with no illustrations. To conduct an experiment, the professor will assign some students to the control group with a reading assignment in paragraph form and other students to the treatment group with a reading assignment in graphic novel form. Afterwards, all the students will take a quiz about the reading to measure comprehension. To assign the groups, the professor will split the students into five groups according to their current grade in the class: A, B, C, D, or F. Within each group, half of the students will be assigned to the treatment group with the graphic novel, and the rest will be assigned to the control group with the paragraph.

A restaurant chain would like to measure the proportion of customers who are generally satisfied with the service provided by its staff. At the end of the meal, as the check is delivered to the table, the server asks those at the table to rate their satisfaction with the service provided as "Very Satisfied,” "Satisfied,” or "Not Satisfied.” During a one-week period, 147 customers were surveyed and 135 (93%) reported they were either Satisfied or Very Satisfied. How might the results be biased in obtaining an estimate of all customers who are satisfied with service?

An automotive service center would like feedback on its customer service. Each customer receives a printed card after they pay for services with a short survey on which customer service is ranked on a scale from 1 (least satisfied) to 5 (most satisfied). Customers can then choose to submit the card in a box on their way out of the store. The store manager finds that 140 cards were filled out in the past week, with an average customer satisfaction score of 2.47. Which type of bias is most likely to be present in the survey results?

A researcher is comparing the effectiveness of three devices designed to help people who snore. There are 210 people who snore participating in the experiment. Using a table of random digits starting from the first row and column, the researcher will randomly place the participants into three equally sized treatment groups suitable for comparison.

The CEO of a company wants to determine if taking the employees to a company retreat would boost their morale. He decides to use a random number table to survey a simple random sample of 50 of the 250 employees. Which of the following correctly labels the population of employees?

A citizen wants to propose to the city council extending the hours at the local public library on some weekdays. To measure support for extended hours, the citizen visits neighborhood homes and asks adults the following: "Would you agree that the closing time of the library should be extended by one hour on weekdays to accommodate working families?” Of the 212 adults surveyed, 86% agreed with the statement. Which of the following statements about the results is true?

A restaurant critic for a newspaper examines the prices restaurants charge for their meals and discovers that the restaurants that raised their prices most over the past year also have the longest wait times for tables.

The difference between an observational study and an experiment is that

A high school student volunteers to present a report to the administration about the types of lunches students prefer. He surveys members of his class and records their choices. What type of sampling did the student use?

A greenhouse owner wants to test the effectiveness of a new fertilizer on African violets. She has 60 violet seedlings that were grown for 8 weeks. She wants to test the new fertilizer on 10 of the plants, and decides to use a simple random sample to select them. Which of the following statements is true?

Several members of a running club would like to survey the rest of the members to determine which 5K races the club should enter. They decide to use a random number table to sample 10 of the 78 members. The members are assigned the numbers 01–78. Refer to the given line from a random number table. Which numbers represent the first 5 members selected?24000 75983 62200 91518 11198 88936

Many golfers wear wrist bracelets containing magnets because they claim the magnets improve balance and the length of shots played off the tee. A golfer would like to determine if the claim has merit and finds 200 volunteers who play golf to participate in an experiment. Half of the golfers are randomly assigned to wear a bracelet with magnets, while the other half wear a bracelet without magnets. Each golfer plays normally for a month, after which the length of their shots in a subsequent round is recorded.

Alejandro wants to determine the average shoe size of all of the male students in his school. Which sample is likely to yield the most biased results?