Question 218177: The mean height of a certain kind of plant is 136 centimeters. Suppose we want to carry out a hypothesis test to see if the mean height when these plants are treated with a certain chemical differs from 136 . State the null hypothesis and the alternative hypothesis that we would use for this test.
Answer by Theo(13342)   (Show Source):
You can put this solution on YOUR website! The null hypothesis would be that the treatment with a different chemical doesn't change a thing and that the plant height remains the same.
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The alternative hypothesis would be that it does.
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You would then take samples of the plants treated with a certain chemical and get a mean of their height.
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Let's say the mean of these plants was 135 centimeters.
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You would then have to determine whether the difference in the mean of the plants that were chemically treated is statistically significant.
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If the difference could be explained by just variation in samples taken, then you would say that the results were not statistically significant.
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If the difference could not be explained by just variation in samples taken, then you would say that the results were statistically significant.
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Statistically significant is normally determined by whether a certain percentage of samples taken are expected to be within certain limits. A generally accepted percentage would be 95%.
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If you get a mean of 135 in a set of samples, and it is determined that 50% of the samples taken could have a mean of 135 or less given a population mean of 136, then the results might not be considered statistically significant.
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If you get a mean of 135 in a set of samples and it is determined that less than 5% of the samples taken could have a mean of 135 or less given a population mean of 136, then the results might be considered statistically significant.
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