### Test a Claim About a Mean for weight loss: Sigma Not Known

Is the Diet Practical? When 40 people used the Weight Watchers Diet for one year, their mean weight loss was 3.0 lb and the standard deviation was 4.9 lb. Use a 0.01 significance level to test the claim that the mean weight loss is greater than 0 lb. Based on these results, does the diet appear to be effective? Does the diet app