Multiple Choice Question

[AlexKom]

Hello!

Here is the problem:

A group of eight people work on the 5th floor of the building.They all decide they want to lose weight by increasing their physical activity. Four of them decide to walk up the five flights of stairs each work day. The other four decide to walk down the five flights at the end of the day. They weight themselves each Monday morning and report their weigh to their supervisor. This is an example of:
A) an experiment since the workers are devided into two equal goups
B) an observational study since the supevisor didn't decide which group walked up the stairs
C Block design, since there are two treatments
D) A survey
E) an explanatory variable
I think that B) is the answer, is it?
Thank you very much!

[AlexKom]

Here is another multiple choice problem:
A new dietary supplement was given to a volunteer group of 25 people who were at least 50 pounds overweight. 18 people from the group lost at least 20 pounds. What can we conclude about the effectiveness of the diet?

A) The diet was effective in 72% of the cases
B) The mean wight loss was more than 20 pounds
C) Nothing since 25 people were not an SRS
D) Nothing since there were no control group that reieved a placebo
E) Nothing since the group knew they were usind the diet

I think that D) is the right answer. Can you help me?

Thank you!

[AlexKom]

A marine biologist wants to determine the best treatment to eliminate a water- borne parasite on salmon. There are 40 Pacific salmon and 60 Atlantic Salmon. Which of the following is a valid reason to use a block design for this experiment?

A) the conclusion can apply equally to both species
B) There is a genetic difference between the two species
C It is a requriment of a double blind experiment
D) Each species may respond diffferently to the treatments
E) There might be different parasites in each ocean

I think that the right answer is either D) or E). I think D) is the best answer.
Is it?

Thank you

[JohnM]

For the first question, it is B, since they weren't assigned to the groups at random.

The second and third are D.

[quark]

I got B, D, D too.