A paint manufacturer wanted to compare the drying times of two different types of paint. Independent simple random samples of 11 cans of type A and 9 cans of type B were selected and applied to similar surfaces. The drying times in hours were recorded. The summary statistics are as follows.
Type A
X1 =70.4
S1=3.2
n1=11

Type B
X2=67.8
S2=3.5
N2=9

Determine a 99% confidence level for the difference between the mean drying time of type A and the mean drying time of type B