1.) A random sample of 50 boys showed that average length of time (in minutes) boys talked on phone was 21 minutes. The population standard deviation for boys is 2.1 minutes. An independent random sample of 50 girls showed average length of time in minutes. Determine a 95 % confidence interval for difference in population mean time spent upon the telephone between boys and girls. Suppose normal distributions.
2.) In a sample of 200 men, 130 said they employed seat belts. In sample of 300 women, 163 said they employed seat belts. Test the claim that the proportion of men who employ seat belts is higher than the proportion of women who employ seat belts. Employ the p-value approach and significance level of 1%.