Question

A sample of 38 babies in the zinc group had a mean birth weight of 3328 grams. A sample of 31 babies in the placebo group had a mean birth weight of 3406 grams. Assume that the population standard deviation for the zinc group is 640 grams, while the population standard deviation for the placebo group is 851851 grams. Determine the 99% confidence interval for the true difference between the mean birth weights for "zinc" babies versus "placebo" babies.

Required:
Find the point estimate for the true difference between the population means.

Answer 1

-78

Explanation:

Zinc group :

Mean, x1 = 3328

σ1 = 640

Sample size, n1 = 28

Placebo group :

Mean, x2 = 3406

σ2 = 851

Sample size, n2 = 31

The point estimate for the true difference between the population means is obtained as :

Mean difference between population :

x1 - x2 = 3328 - 3406 = - 78