1. a study of college freshmen found that students who watched tv for more than one hour each night gained 15 pounds in the first semester, compared to those who watched less than one hour. they concluded that there is an association between watching tv and weight gain in college freshmen. which study design did they most likely use?

they most likely used an experiment with students randomly assigned to watch more than one hour or less than one hour of tv each night.

they most likely used an experiment with students randomly assigned to groups based on how much weight they gained.

they most likely used an observational study asking students to keep track of their tv habits and weight.

they most likely used an observational study asking students to keep track of their workout regimen and weight.

2. a teacher interested in determining the effect of a new computer program on learning to read conducted a study. one hundred students were randomly assigned to one of two groups. the first group used the computer program while the second group did not. both groups were tested to determine how much their reading levels improved. the results for the two groups were compared. what kind of study is this?

this is an experiment because a treatment was applied to a group.

this is an experiment because students were able to choose which group to join.

this is a survey because students were randomly assigned to groups.

this is a survey because a treatment was applied to both groups.