=+43. The joint distribution of the number of cars (x) and the number of buses (y) per signal cycle at a particular left turn lane is displayed in the accompanying table:

y f(x, y) 0 1 2 0 .025 .015 .010 1 .050 .030 .020 x 2 .125 .075 .050 3 .150 .090 .060 4 .100 .060 .040 5 .050 .030 .020