A county engineer would like to determine if a speed reduction strategy has been effective. She performs a second speed study to compare with one done before the strategy was implemented. The collected data has the following characteristics. u1 = 36.6 mi/h S1 = 8.0 mi/h n1 = 30 u2 = 34.0 mi/h S2 = 9.8 mi/h n2 = 30 Determine if there is a statistically significant decrease in speeds with a 95% confidence level using first the t-test and then the Z-test. (Assume the decrease in speeds is statistically significant if the second speed is not within the 95% confidence level of the first speed.) Yes, there is a statistically significant difference. No, there is not a statistically significant difference