Question

There is a weight control program that claims that in three weeks people can lose 10 pounds. One researcher submitted 10 people to the program and found the following results:

Person	1	2	3	4	5	6	7	8	9	10
Weight at the start	160	169	200	145	185	192	145	165	128	215
Weight at the end of the 2 weeks	155	160	180	140	170	180	150	152	120	201

a. Calculate a confidence interval for the difference in weights.
b. Do you believe that the company's claim is valid?

Answer 1

The Calculation table is given below:

Start	End	d =start-end	d^2
160	155	5	25
169	160	9	81
200	180	20	400
145	140	5	25
185	170	15	225
192	180	12	144
145	150	-5	25
165	152	13	169
128	120	8	64
215	201	14	196
	Total	96	1354

a) 95% Confidence Interval

The 95% Confidence interval is = ( 4.64, 14.56)

b) Since the difference in weight i.e. 10 pounds( hypothetical weight) is included in tha confidence interval limits. we believe that the company;s claim is valid.