Question

The birth weights for two groups of babies were compared in a study. In one group the mothers took a zinc supplement during pregnancy. In another group, the mothers took a placebo. A sample of 72 babies in the zinc group had a mean birth weight of 3072 grams. A sample of 158 babies in the placebo group had a mean birth weight of 3426 grams. Assume that the population standard deviation for the zinc group is 792 grams, while the population standard deviation for the placebo group is 708 grams. Determine the 95% confidence interval for the true difference between the mean birth weights for "zinc" babies versus "placebo" babies.

Step 2 of 3 :  

Calculate the margin of error of a confidence interval for the difference between the two population means. Round your answer to six decimal places.

Answer 1

The detailed solution is given below.