Final answer:
To find the value of c for the joint probability density function, set up the double integral of c(x + y) over x and y from 0 to 1 and solve for c such that the total area under the curve is 1. Subsequently, this function can be used for various probability and expectation calculations.
Step-by-step explanation:
The student is asking to find the value of c that makes the function f(x, y) = c(x + y) a joint probability density function (PDF) over the range 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1. To ensure f(x, y) is a PDF, the double integral of f(x, y) over the range of x and y must equal 1. By calculating the double integral, we find the constant c that satisfies this condition.
Let's perform the integration:
- Set up the double integral ∫∫D f(x, y) dx dy, where D is the domain 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1.
- Integrate f(x, y) = c(x + y) first with respect to x from 0 to 1, then with respect to y from 0 to 1.
- Solve for c to make the total area (total probability) equal to 1.
Note that after determining c, you can use this density function to calculate various probabilities and expectations such as P(X > 1, Y > 2), E(X), E(Y|X = 1), V(X), and marginal probabilities.