sentences:  For the exponential distribution, this is just "e"−"x"1, while for the normal distribution, assuming you are using the unnormalized "f"("x") = "e"−"x"2/2, this is  erfc("x"/).For more awkward distributions, numerical integration may be required.With this in hand, from "x"1, you can find "y"1 = "f"("x"1), the area "t" in the tail, and the area of the base layer "A" = "x"1"y"1 + "t".