Unit Test — Unit test Answers

A biology student wants to determine if using a fertilizer would help promote growth of new babies in spider plants. The student has access to 90 spider plants of three varieties: green, variegated, and curly. They all are potted in the same amount and type of soil, given the same amount of water, and exposed to the same amount of light. After one year, the shoots will be counted for each plant.

A biologist wonders if the life span of bats will be affected by two new food sources from invasive species moving into an area. To conduct the experiment, the biologist needs three treatment groups: a group where the diet will not include invasive species (control), a group where the diet will include one invasive species (treatment group 1), and another group where the diet will include the other invasive species (treatment group 2). The biologist chooses the first cloud-free night and catches the first 18 bats that fly out of a cave, placing them into three equal groups of six bats. To decide the treatment for each group, the biologist places three slips of paper labeled control, treatment group 1, and treatment group 2 in a hat and randomly selects 2 slips of paper. The first piece of paper gives the treatment for the first group, the second piece of paper gives the treatment for the second group, and the remaining treatment is given to the third group.

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 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.

A veterinarian knows that the supplement glucosamine is beneficial for dogs’ joints. He wants to determine if a supplement with both glucosamine and chondroitin would be more beneficial than glucosamine alone for dogs’ joint health. The veterinarian asks the owners of dogs with known joint issues if they would be willing to have their dog participate in his study, and 32 owners agree to the study. The dogs’ names are written on equal-sized slips of paper. The veterinarian selects the first 16 slips of paper. These dogs are given the glucosamine treatment.. These dogs are given the glucosamine treatment. The other 16 dogs are given the glucosamine with chondroitin treatment. After six months, the dogs’ joint health is measured for each treatment and compared.

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?

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.

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. A golf pro randomly selects a ball, not knowing which type is chosen, and hits it. The difference in mean distances traveled (new – original) for the samples was 2.6 feet. Assuming there is no difference in distance traveled between the two types of golf balls, 200 simulated differences in sample means are displayed in the dotplot.

In an activity, students are pulling marbles from a large jar containing blue and red marbles. In their sample, students will calculate the proportion of blue marbles. Which of the following sample sizes will have the largest sampling variability?

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.

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 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?

A florist wants to determine if a new additive would help extend the life of cut flowers longer than the original additive. The florist randomly selects 20 carnations and randomly assigns 10 to the new additive and 10 to the original additive. After three weeks, 6 carnations placed in the new additive still looked healthy and 2 carnations placed in the original additive still looked healthy. The difference in proportions (new – original) for the carnations that still looked healthy after three weeks was 0.4. Assuming there is no difference in the additives, 200 simulated differences in sample proportions are displayed in the dotplot.

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.

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 shoe company wants to test an updated model of a running shoe on its wear after one month of running. They recruit 50 people who run on a regular basis to participate in their study. They will have the runners wear the shoes when they run for two months. After two months, the wear on the shoes will be determined using the depth of the tread and flexibility of the toe box. The wear between the new model and the original model will then be compared.

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.

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.

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 consumer agency wants to determine which of two laundry detergents, A or B, cleans better. Fifty 1-square-foot sections of fabric are randomly selected and cut from different bolts of fabric. They are then subjected to the same kinds of stains (grass, mud, coffee). Then 25 pieces are randomly assigned to be cleaned with detergent A, and the remaining 25 pieces are cleaned with detergent B. After being laundered, the pieces of fabric are rated on a scale of 1–10, with 1 being the least clean to 10 being the most clean. The mean rating for detergent A is found to be significantly greater than the mean rating for detergent B.