With steps please

Suppose that every man's age (X) is exactly 7 years greater than his wife's age (Y). Mathematically, X= Y+7; Then the correlation coefficient between X and Y is equal to: In a population of students, the number of calculators owned is a random variable X with P(X = 0) = 0.2, P(X = 1) = 0.6, and P(X = 2) = 0.2. The Variance of this probability distribution is: The continuous random variables X and Y have the following joint density function: f(x.y)- 2 05x10sys10sx+ysl elsewhere The marginal density of Y is : Suppose X a random variable with the following probability density function. What is the expression of the Cumulative Distribution Function? if x 2