SOLUTION: Find k so that f (x, y) = kxy, 1 ≤ x ≤ y ≤ 2 will be a probability density function. Also find (i) P(X ≤ 3/2 , Y ≤ 3/2 ), and (ii) P(X + Y ≤ 3/2 ). Thank you :)

Algebra ->  Probability-and-statistics -> SOLUTION: Find k so that f (x, y) = kxy, 1 ≤ x ≤ y ≤ 2 will be a probability density function. Also find (i) P(X ≤ 3/2 , Y ≤ 3/2 ), and (ii) P(X + Y ≤ 3/2 ). Thank you :)      Log On


   



Question 1178058: Find k so that f (x, y) = kxy, 1 ≤ x ≤ y ≤ 2 will be a probability density function. Also find (i) P(X ≤ 3/2 , Y ≤ 3/2 ), and (ii) P(X + Y ≤ 3/2 ).
Thank you :)

Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
Must have ==> k+=+4%2F9.
(i)

(ii) Quickly sketching the region defined by +x%2By+%3C=+3%2F2 as well as the square region [1,2]x[1,2], you will see that these two regions do not intersect at all. Hence P%28X%2BY+%3C=+3%2F2%29+=+0.
***In general, for this problem, p%28x%2Cy%29+=+%281%2F4%29%2A%28x%5E2+-+1%29%28y%5E2-1%29,
where 1+%3C=+x+%3C=+2 and 1+%3C=+y+%3C=+2.