Question

An advertisement for a diet program described a study performed on 70 obese adults. Each person in the study was weighed before beginning the diet and then 5 weeks after starting the diet. The difference was recordeddasha positive value indicates a person lost weight on the diet while a negative value indicates the person gained weight while on the diet. The advertisement gave a​ 95% confidence interval for the average weight change while on the​ diet: ​(minus​1,5) lbs. The advertisement says that this shows the diet works at reducing weight for obese adults since more people lost weight than gained weight. What conclusion can be made about the weight loss​ program?

A. Their interpretation of the confidence interval is correct.

B. Their interpretation of the confidence interval is not correct. Because the lower bound is​ negative, some people did gain weight which means that we​ can't claim the diet works at reducing weight for all obese adults.

C. Their interpretation of the confidence interval is not correct. Because 0 is in the​ interval, there is no evidence to indicate that the average weight loss is more than 0 for obese adults.

D. Their claim that the diet works is​ accurate, but for the wrong reason. Because 0 is in the​ interval, there is evidence to indicate the average weight loss is more than 0 for obese adults.

Answer 1

The correct answer is -

B. Their interpretation of the confidence interval is not correct. Because the lower bound is​ negative, some people did gain weight which means that we​ can't claim the diet works at reducing weight for all obese adults.

Reasoning -

It is given that the confidence interval is (-1,5). And it is given that negative value indicates the person gained weight while on the diet. Thus, out of confidence interval (-1,5) the part (-1,0) does not support the interpretation that diet helps in weight loss.