4. A compact fluorescent light (CFL) bulb manufacturer advertises their bulbs have a brightness of 825 lumens. Their Quality control department tests the brightness of 14 randomly selected bulbs. The brightness in lumens of each tested bulb is given below. 838 822 823 838 818 829 841 806 821 820 827 821 843 823 a. Is there sufficient evidence that the true mean brightness of the bulbs is different than advertised? Use a = 0.01. b. The power of this test to detect 1.: = 815 is 0-85. Explain what this means in context. c. Explain two ways to increase the power of this test. d. If p = 810, would the power of the test decrease, increase of stay the same? Explain