# Homework Help: Statistics 101 problem. Using confidence values and z scores?

1. Jun 6, 2007

### famtrecrew

1. A study of zinc-deficient mothers was conducted to determine whether zinc supplemnetation during pregnancy results in babies with increased weight at birth. The weights are measured in grams. Use a 0.05 significance level to test the claim that zinc supplementation does increase weight at birth

2. Zinc group: n=294 xbar=3214 s=669

Placebo Group: n=286 xbar=3088 s=728

3. I tried using z scores to figure this out by using the equation z= xbar-m/sigma/[squareroot of n] however i am not sure if i need some sort of hypothesis testing or how to go about solving this. Since i dont know m I was using the xbar1-xbar2 on the numerator. Any help is appreciated. The answer i got was using Hnot: m<=0 and H1: m>0. Then getting 1.96 and a calculated z score of 3.229. Since 3.229>1.96 I stated that we reject Hnot and which means that m is greater than 0 showing a positive weight gain in the zinc supliment catagory. I think that this is wrong though.

2. Sep 7, 2007

### EnumaElish

Last edited: Sep 7, 2007