Unit Test — Unit test Answers

A florist wants to determine if a new additive would extend the life of cut flowers longer than the original additive. The florist selects the first 20 carnations from the ones recently delivered by the greenhouse and assigns the first 10 to the new additive and the rest 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 proportion of healthy carnations with the new additive was significantly greater than the proportion of healthy carnations with the original 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.

A new cream was developed to reduce the irritation caused by poison ivy. To test the effectiveness, researchers placed an ad online asking volunteers to participate in the study, and 100 subjects replied. They are informed that one group will receive a new cream and the other group will receive a cream with no active ingredient. The researchers believe that sun exposure may affect the cream’s effectiveness. The subjects are then asked about their outdoor activity, and 42 of the subjects state they spend more than 50% of their day outside. The 42 subjects are randomly assigned to the two treatments. The remaining 58 subjects are also randomly assigned to the two treatments. All subjects are exposed to poison ivy and given their cream. They are asked to return in three days and report their level of irritation.

A tire company wants to determine if tires made with a new type of tread will last longer than tires made with the original type of tread. The company has access to 20 different vehicles and wants to use a randomized block design for the experiment.Which of the following variables would be the best to block the experimental units?

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. The first six bats will be the control group, the second six will be treatment group 1, and the last six will be treatment group 2.

A researcher is comparing the effectiveness of three devices designed to help people who snore. There are 60 people who snore participating in the experiment who are labeled 01–60. Using a table of random digits, the researcher will randomly place the participants into three equally sized treatment groups suitable for comparison. Carry out the random assignment using the given selection from a table of random digits, starting with the first row and first column.

What proportion of families own as opposed to rent their home? To find out, an urban planner selected a random sample of 400 families in a large city to participate in a survey about homeownership. Of the 362 families that responded to the survey, 42% reported that they own their home. Which of the following statements about the survey results is true?

A trade school would like to measure the long-term success of their graduates after they leave the school. The school emails a survey requesting information from graduates about their work experience. One question asks graduates to share their annual salary, and the results of the question will be shared in a brochure for incoming students. Is it likely that the survey results will provide an accurate estimate of mean annual salary for all of the school’s graduates?

A therapist wants to study the effects of yoga and meditation on stress relief. She has 60 volunteers who experience varying levels of stress. Half of the participants will be assigned to practice yoga for one month and the other half will practice meditation. Before the experiment begins, all of the participants will be asked to rate their stress levels on a scale from 0 to 10, with 0 representing "no stress” and 10 representing "highest level of stress.” At the end of one month, the participants will be asked to rate their stress levels again. The differences in stress levels will be compared.

A biology student wants to determine if using a fertilizer would help promote growth of new babies in spider plants. The student chooses 100 baby spider plants to be used in the study. 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. Fifty of the plants will be given the fertilizer treatment and the other 50 plants will not receive any fertilizer. After one year, the shoots will be counted for each plant.

An article in a psychology journal claims that young students who play a musical instrument tend to have higher test scores on state math exams. To assess the claim, a government official considers two methods to collect data.Method 1: Contact many city schools and ask them to provide summary data on state math exam performance and students who participate in music lessons.Method 2: Choose two city schools and provide free music lessons to students who register. At the end of the year, compare state math exam scores for students who participated in the music lessons with the scores for those who did not.

An urban planner examines police-report data for many cities and towns and discovers that cities with professional football teams tend to have higher numbers of reported small crimes, such as burglary.