12. (6pts) A professor believes that on average, 15% of their students receive A's, 25% receive B's, 30% receive cs 20% receive D's, and 10% receive F's. In a sample of 100 students, the following grades were observed: Category Observed Frequency A 9 B 35 C 29 D 1 2 F l 5 (a) Assuming that the professor's belief is true, compute the expected frequencies. (b) Use Excel to compute the Pvalue for the chisquare goodnessoffit test. Round to three decimal places. (c) State the conclusion of the test using the a : 0.05 signicance level