In a study conducted by researchers. 79 subjects were administered the zone diet
ID: 3234932 • Letter: I
Question
In a study conducted by researchers. 79 subjects were administered the zone diet. After 12 months, the mean weight loss was 1.6 with a standard deviation of 5.4 kg. Do the results suggest that the mean weight loss was greater than at the 0.5 level of significance? In 1997, 11% of adult Americans had no faith that the federal government was capable of effectively dealing with domestic problems. In a survey in 2007 by the Gallup organization of 1, 100 adult Americans, 143 had no faith that the federal government was capable of effectively dealing with domestic problems. Test whether the proportion has changed since 1997 at the alpha = 0.10 level of significance.Explanation / Answer
Given sample size is n=79
Xbar=1.6 & s=5.4
We have to test the hypothesis that whether the mean weight loss was greater than zero.
We use z-test,
Null hypothesis: mu=0
Vs
Alternative:mu>0
Z= (Xbar -mu)/(s/sqrt(n))
= 1.6*sqrt(79)/5.4
=1.6*8.88/5.4
Z =2.63
We have to find out the critical value of z.
As this is one tail test at 5% level of significance
as the calculated value of z is greater than critical value of z we
Reject null hypothesis at 5% level of significance.
Therefore the mean weight loss is greater than zero.