1.20

Indicate whether the following study is an observational study or a controlled experiment.

A researcher is interested in the effect of music on memory. She randomly divides a group of students into three?groups: those who will listen to quiet?music, those who will listen to loud?music, and those who will not listen to music. After the appropriate music is played?(or not?played), she gives all the students a memory test.

Select the correct answer below.

A.

This is a controlled experiment. She assigns students to the control and treatment groups at random in order to control for all relevant factors aside from the effect of music on?memory, which is essential to conducting a controlled experiment.

B.

This is an observational study. The number of treatment groups is not sufficiently large to control for all relevant factors aside from the effect of music on?memory; a large number of treatment groups is essential to conducting a controlled experiment.

C.

This is an observational study. The researcher observes only the results of the memory test. Without observing the?subjects' performance on memory tests prior to assignment to different?groups, the study is not sufficiently active to make this a controlled experiment.

D.

This is a controlled experiment. She controls for other factors prior to assigning students to the control group and two treatment groups. This is essential to conducting a controlled experiment.

1.21

The dotplot shows the body mass index?(BMI) for 140 randomly surveyed people from a certain country.

a. A BMI of more than 40 is considered morbidly obese. Report the number of morbidly obese shown in the dotplot.

b. Report the percentage of people who are morbidly obese. Compare this with a recent estimate that?3% of people from the country were morbidly obese.

16 32 64 20 24 28 36 40 44 48 52 56 60 BMIAnimal Longevity Animal Lifespan (Years) @ Pig, domestic 10 Wolf, maned 5 Horse 20 Leopard 12 Bear, grizzly 25 Puma 12 Gorilla 20 Lion 15 Elephant, African 35 Hippo 41 Baboon 12 Cat, domestic 12 Giraffe 10 Zebra, Grant's 15Elk 16 Rhino, black 15 Tiger 16