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. Use the table to complete parts a through c. Later-Born First-Born Sample mean 425.7 547.0 Sample standard deviation 133.8 133.7 Sample size 13 13 Construct a 95% confidence interval to estimate the difference between the average number of words understood by first-born and later-born one-year-old hildren. he 95% confidence interval is ( Round to two decimal places as needed.)