9. The following data relate to the ages at death of a certain species of rats that were fed 1 of 3 types of diet. Thirty rats of a type having a short life span were randomly divided into 3 groups of size 10 each. The sample means and sample variances of the ages at death (measured in months) of the 3 groups are as follows:

Test the hypothesis, at the 5 percent level of significance, that the mean lifetime of a rat is not affected by its diet. What about at the 1 percent level?

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Sample mean Sample variance Very Low Calorie Moderate Calorie High Calorie 22.4 24.0 16.8 23.2 13.7 17.1