The water diet requires one to drink two cups of water every half hour from when
ID: 2958078 • Letter: T
Question
The water diet requires one to drink two cups of water every half hour from when one gets up until one goes to bed, but otherwise allows one to eat whatever one likes. Four adult volunteers agree to test the diet. They are weighed prior to beginning the diet and after six weeks on the diet. The weights (in pounds) are
Person
1
2
3
4
Weight before the diet
180
125
240
150
Weight after six weeks
170
130
215
152
For the population of all adults, assume that the weight loss after six weeks on the diet (weight before beginning the diet minus weight after six weeks on the diet) is normally distributed with mean (µ).
When testing the claim that the diet leads to weight loss after six weeks for all adults given that =0.05, do you reject or fail to reject the Null Hypothesis, why or why not?
Person
1
2
3
4
Weight before the diet
180
125
240
150
Weight after six weeks
170
130
215
152
Explanation / Answer
We should use a 1-tailed t-test
H0= The mean difference weight after the 6 week period for all adults is not significantly less than 0.
HA: The mean difference weight after the 6 week period for all adults is significantly less than 0.
The data (differences of week 6 minus initial) are as follows:
-10
5
-25
2
The mean is -7 pounds, with a standard deviation of 13.64
The t-value is -1.0265 and the corresponding p-valueis .19
At the .05 significance level, we cannto conclude that the mean weight loss is significantly less than 0. Thus, we fail to reject the null hypothesis.
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