Paint used to paint lines on roads must reflect enough light to be clearly visible at night. Let µ denote the mean reflectometer reading for a new type of paint under consideration. A test of H0: µ = 20 versus Ha: µ > 20 based on a sample of 15 observations gave t = 3.2. What conclusion is appropriate at each of the following significance levels?
a. a = .05
b. a = .01
c. a = .001