Help again? (please dont just give me the ansers can you please explain it)?

Question

A teacher gives 2 mice viatimin c everyday for one month and a sugar pill to another twenty mice every day for a month. ALl the mice are fed once a day. what is not a constant experiment

A. the vitamin c
B. the frequency of feeding
C. the number of mice
D. the number of days the mice will recieve vitamin c

Answer 1

Look at the words in the problem.

- You said all the mice are fed once a day so that means B can't be the answer.
- You only give one time, a month, as the time period so that means D can't be the answer.
- You didn't say that any mice were removed or killed so the number of mice is constant, which means C can't be the answer.

That leaves you with A as your answer. Only 2 mice were given Vitamin C, the rest were given sugar pills. That is inconstant so that is your answer. In this case the way to solve the problem was to see what was wrong as an answer; what didn't fit.

The question relates to constants in an experiment. When you do an experiment you need as many constant variables as possible to rule them out. If every subject does this then subjects with different results can't have gotten those results from doing the same thing. Do you see what I mean?

At first glance D seems to be the answer because only 2 mice got it, but they got it for the entire experiment which rules D out as an answer. If this was an experiment on the mice to see what the vitamin C did then you would look for the differences between those 2 mice and the other 20. The other 20 is your control group. In an experiment you use a control group to account for unknown factors.

For example if you feed 22 mice for a month and weigh them. If you feed 2 vitamin C, 2 sugar pills, 2 something else and so on. Then you want to have a group that is feed normally. If those mice get fat then you can't say the vitamin C or the sugar made your mice fat, because the control group got fat as well. If you see the vitamin C eating mice and the control group as lean, but the ones eating sugar pills are getting fat then you can conclude that the difference is the sugar pills. The control group helps you eliminate other errors or factors that could creep into the experiment.