We wish to see if on average traffic is moving at the posted

We wish to see if, on average, traffic is moving at the posted speed limit of 65 miles per hour along a certain stretch of Interstate 70. On each of four randomly selected days, a randomly selected car is timed and the speed of the car is recorded. The observed speeds are 70, 65, 70, and 75 miles per hour. Assuming that speeds are Normally distributed with mean , we test whether, on average, traffic is moving at 65 miles per hour, by testing the hypotheses H0: = 65, Ha: 65. Reference: Based on these data,

A. we would reject H0 at significance level 0.025 but not at 0.01.

B. we would reject H0 at significance level 0.01.

C. we would reject H0 at significance level 0.10 but not at 0.05.

D. we would reject H0 at significance level 0.05 but not at 0.025.

Solution