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 34 babies in the zinc group had a mean birth weight of 3276 grams. A sample of 31 babies in the placebo group had a mean birth weight of 3064 grams. Assume that the population standard deviation for the zinc group is 660 grams, while the population standard deviation for the placebo group is 505 grams. Determine the 95% confidence interval for the true difference between the mean birth weights for "zinc" babies versus "placebo" babies.

Step 1 of 3: Find the point estimate for the true difference between the population means.

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.

Step 3 of 3: Construct the 95% confidence interval. Round your answers to the nearest whole number.

Answer 1

The statistical software output for this problem is :

Step : Point estimate = 212

Step 2 : margin of error = 284.285178

Step 3 : The 95% CI is :

-72 to 496