# A biologist

A biologist knows that the average length of a leaf of a certain plant is 4 inches. The standard deviation of the population is 0.6 inch. A sample of 20 leaves of that type of plant given a new type of plant food had an average length of 4.2 inches. At level α =0.01, is there reason to believe that the new food is responsible for a change in the growth of leaves?

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