=+19. The paint used to make lines on roads must reflect enough light to be clearly visible at night. Let  denote the true average reflectometer reading for a new type of paint under consideration. A test of H0:  5 20 versus Ha:  . 20 will be based on a random sample of size n from a normal population distribution. What conclusion is appropriate in each of the following situations?

a. n 5 15, t 5 3.2,  5 .05

b. n 5 9, t 5 1.8,  5 .01

c. n 5 24, t 5 2.2