Researchers randomly choose two groups from 15 volunteers. over a period of 9 weeks, one group watches television before going to sleep, and the other does not. volunteers wear monitoring devices while sleeping, and researchers record dream activity. which type of study method is described in each situation?
a. not enough information given.
b. observational study
c. survey
d. controlled experiment

Option D. Controlled experiment

Step-by-step explanation:

A. The information given is sufficient to identify the type of study method in each situation.

B. In observational study, the researcher has no control over the variables and no treatment is applied on the variables. But in case 1, only one group is allowed to watch television (controlled) and in case 2 volunteers wear monitoring devices while sleeping ( treatment is applied ) so not observational study

C. Survey study includes collecting the information or data as reported by the individuals but in the given situations the volunteers are not reporting any information to the researchers instead they are monitored and controlled by the researchers. So, not survey study

D. A controlled experiment is one in which the variables are manipulated by the researchers and here in all the cases the researchers are controlling the volunteers in one way or other so in both the situations controlled experiment study is described

Hence, the option D is appropriate.

answer: given that the roller coaster can accommodate 1600 riders per hour, thus the roller coaster can accomodate 1600 / 60 = 26.67 riders per minute.

given that there are 345 people in the line, the number of minutes it will take for the 345 persons to get into the roller coaster is given by 345 / 26.67 = 12.94 minutes.

therefore, it will take you 12.94 minutes to get to the front of the line.

step-by-step explanation:

what? ?

what type of question is thiss

step-by-step explanation: