Question 1205407
Soln : marginal of x has two values for x=2 and x=4

For x = 2, we need to find sum of all y values over x=2 
i.e. (2,1)+(2,3)+(2,5) = 0.1 + 0.2 + 0.1 = 0.4

For For x = 4, we need to find sum of all y values over x=4 
i.e. (4,1)+(4,3)+(4,5) = 0.15 + 0.3 + 0.15 = 0.6 

To check marginal pdf of x sum to 1 = 0.4+ 0.6 


Similarly, 
marginal of y has three values for y=1, y=3 and y=5

For y=1, we need to find sum of all x values over y=1 
i.e. (2,1)+(4,1) = 0.1 + 0.15 = 0.25

For y=3, we need to find sum of all x values over y=3
i.e. (2,3)+(4,3) = 0.2 + 0.3 = 0.5

For y=5, we need to find sum of all x values over y=5 
i.e. (2,5)+(4,5) = 0.1 + 0.15 = 0.25

To check marginal pdf of y sum to 1 = 0.25+ 0.5 + 0.25