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How many plants do we need to test how chlorine effects plant growth and how much do we put in each plant?
Question Date: 2015-12-23
Answer 1:

Those are good questions. Testing one level on one plant doesn’t tell you anything because each individual plant is different. You also need to compare plants that are alike in every way except for the amount of chlorine. You could have a series of amounts of chlorine, such as none, a little, medium, and high, then have two or three plants at each level. The big question is what level is high or low. I could see if anyone has tested anything like this if you tell me what sort of plant you’re using. That could give you an idea of the range of chlorine levels you might try. Some plants are probably much more sensitive to chlorine than other plants are.

Thanks for asking.

Answer 2:

That question doesn't have a simple answer.

More plants to do the experiment means that you can be more sure of your results. If you don't have enough plants, it could be just chance. However, there is no hard number of what is "enough" - no matter how many plants you have, your results could still be just chance, but it is less and less likely the more plants you have.

As for how much you need, that depends on what you want to do with the chlorine. A very small amount of chlorine will be necessary, but too much will be poisonous. By doing an experiment, you will be able to say that some amount of chlorine affects plant growth, and you will also be able to say that some amount of chlorine DOES NOT affect plant growth, both of which are useful questions.

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