He joint density function for a pair of random variables X and Y is given. (Round your answers to four decimal places.) f(x, y) = Cx(1 + y) if 0 ≤ x ≤ 1, 0 ≤ y ≤ 4 0 otherwise (a) Find the value of the constant C. (b) Find P(X ≤ 1, Y ≤ 1). (c) Find P(X + Y ≤ 1).

Grading scale 1 has the following weights- (tests- 50% quiz- 25% homework- 15% final exam- 10%). calculate your final average if your performance in the class is as follows-test grades- {88, 84, 90, 75, 70, 81); quiz grades- {88, 67, 90, 90, 45, 99, 76, 98, 100}; homework- 90; final exam- 75