Nacirema Airlines is buying a fleet of new fuel-efficient planes. The HogJet and the LitheJet both meet their price and performance needs, and both planes meet EPA noise guidelines. However, the quieter plane is preferred. They want to test whether or not there is enough evidence to suggest there is a difference in noise level between the planes.

In order to test the hypothesis, Each plane is flown through a typical takeoff and landing sequence 10 times, while remote sensors at ground level record the noise levels (in decibels). The table below summarizes the sound level tests using Excel's default level of significance (?= 0.05 and assume that the underlying populations distribution of noise level is normal). Is there enough evidence to suggest there is a significant difference (at 5% level) in noise level between the two planes?

t- Test: Assuming Equal Variances t-Test: Assuming Unequal Variances Lithe Jet Hog Jet Lithe Jet Hog Jet Mean 80.3368 82.4669 Mean 80.3368 82.4669 Variance 0.7178 4.7385 Variance 0.7178 4.7385 Observations 10 10 Observations 10 10 Pooled Variance 2.7282 Hypothesized Diff 0 Hypothesized Diff 0.0000 df 18 12 t Stat -2.8837 t Stat -2.8837 P(T