Mucilage is a thick, gluey substance produced by nearly all plants and some microorganisms in sea. Experts claim that due to climate change the amount of mucilage has risen to an alarming level in Marmara Sea for the last two months. In a study conducted by Turkish Institute for Fisheries Research, the influence of mucilage on the circulation levels of oxygen in the blood is examined. Blood samples were taken from red porgy fish living in Marmara Sea around the coastline of industrial city of Krfez, before they are exposed to sea water with high levels of mucilage. Next, a second blood sample was obtained from each fish one hour after they are exposed to sea water with high levels of mucilage. The levels of oxygen at time of first and second sampling, measured in millimeters of mercury (mm Hg), for 10 fish are given in the following table. Oxygen (mm Hg) Fish Before being exposed to mucilage After being exposed to mucilage 1 73 68 2 70 66 3. 74 65 4 68 60 5 87 75 6 76 64 7 69 65 8 74 69 9 77 71 10 80 74 The sample mean and standard deviation for the differences in measurements of the two samplings are 7.1 and 3.03 respectively. Assuming that the populations of oxygen levels at time of two samplings are normally distributed; a) Test at the 0.05 level of significance whether the oxygen concentrations change after being exposed to mercury. b) Why do you think that the test you applied in part (a) is appropriate for this question? c) Display the critical region on the corresponding distribution graph. d) How is the power of test affected if we increase the significance level? Explain.