Question

The General Social Survey collects data on demographics, education, and work, among many other characteristics of US residents. The histograms below display the distributions of hours worked per week for two education groups: those with and without a college degree.

Suppose we want to estimate the difference between the average number of hours worked per week by all Americans with a college degree and those without a college degree. Summary information for each group is shown in the tables.

Statistic	College Degree	No College Degree
Mean	42.1 hours	39.3 hours
SD	14.6 hours	15 hours
n	486	636

1. Create a 99% confidence interval for the difference in number of hours worked between the two groups. Round results to four decimal places.

Answer 1

Mean1 = 42.1

Sample size1 (n1) = 486

Standard deviation1 (s1) = 14.6

Mean2 = 39.3

Sample size2 (n2) = 636

Standard deviation2 (s2) = 15

Confidence interval(in %) = 99

Since we know that

Required confidence interval = (2.8-2.3049, 2.8+2.3049)

Required confidence interval = (0.4951, 5.1049)

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