Question

The company SlimDown makes weight loss products. It has recently come out with a new skin cream that, when rubbed behind the ears, is thought to cause the user to lose weight. To test the cream, a random sample of 49 people was chosen, and the percentage weight loss over an eight week period recorded. Find the power of the test to determine if the the new cream is effective, when the mean percent weight reduction is actually 1.7%. Assume that the population standard deviation is 10% and that the significance level is α=0.01.

Can you please provide the answer via Minitab and show me how it can be calculated by hand? Thanks!

Answer 1

Since N=49,

Percentage change in mean weight is = 1.7% = 0.017 .

Standard deviation() = 10% = 0.10

and significance level is α = 0.01

Here we have to setup the null hypothesis

new cream is not effective in  weight lose

Vs

new cream is effective in  weight lose

The test Statistics used will be Z test

Percentage change in mean weight is = 0.017 .

Since Calculated which is less then ,Hence we will accept our null hypothesis at 0.01 significance level and will conclude that new cream is not effective in  weight lose.