The following table shows the average number of words understood by later born and first born one year old children from two random samples. Assume the population variances of the number of words understood are equal.

a. Construct a 98% confidence interval to estimate the difference between the average number of words understood by first born and later born one year old children.

b. What conclusions can be made about the difference between the two populations?

c. What assumptions need to be made in order to perform this procedure?

Transcribed Image Text:

Later-Born First-Born 430.2 Sample mean Sample standard deviation Sample size 130.8 12 552.0 133.7 12