10.11 An important feature of tablets is battery life, the number of hours before the battery needs to be recharged. The table below contains the battery life of 12 WiFi-only and 7 3G/4G/WiFi 9-through 12-inch tables.

a. Assuming that the population variances from both types of tablets are equal, is there evidence of a difference in the mean battery life between the two types of tablets? (Use = 0.05.)

b. Determine the p-value in (a) and interpret its meaning.

c. Assuming that the population variances from both types of tablets are equal, construct and interpret a 95% confidence interval estimate of the difference between the population mean battery life of the two types of tablets.

WiFi Only	3G/4G+WiFi
12.40	11.70
10.60	11.40
11.50	10.70
12.60	11.50
8.00	11.30
10.90	11.60
11.60	8.90
10.00
10.90
8.90
9.50
10.50