As part of a study to determine whether gender affects dental hygiene habits, a random sample of n = 20 men and a random sample of n = 20 women were asked "How many minutes do you typically spend brushing your teeth each day?" The sample means
of the responses are x1 = 3.6 minutes for men and x2 - 3.8 minutes for women
Assuming the distributions of time spent brushing for both men and women share a known standard deviation of o = 1.2, what is a
95% confidence interval for the difference in mean times?
A)
(-0.64, 0.24
BI
(-0.73, 0.33)
(-0.82,0.42)
D
(-0.94, 0.54)