SOLUTION: Suppose the pdf of the random variable (rv) X is f(x)= c(4x-2x^2) 0<x<2, f(x)= 0 otherwise, a) Find c b) Find P(0.5 < X ≤ 1.5).

Algebra ->  Probability-and-statistics -> SOLUTION: Suppose the pdf of the random variable (rv) X is f(x)= c(4x-2x^2) 0<x<2, f(x)= 0 otherwise, a) Find c b) Find P(0.5 < X ≤ 1.5).       Log On


   



Question 1163972: Suppose the pdf of the random variable (rv) X is
f(x)= c(4x-2x^2) 0<x<2,
f(x)= 0 otherwise,
a) Find c
b) Find P(0.5 < X ≤ 1.5).

Answer by Edwin McCravy(20064) About Me  (Show Source):
You can put this solution on YOUR website!

We have to make the area under the curve from 0 to 2 be 1 unit.
That is, we want the shaded area below to be equal to 1.



So we must find that area, using integration, in terms of c,
set it equal to 1 and solve for c:

int%28%28c%284x-2x%5E2%29%5E%22%22%29%2Cdx%2C0%2C2%29%22%22=%22%22c%2Aint%28%284x-2x%5E2%29%5E%22%22%2Cdx%2C0%2C2%29%22%22=%22%22c%2A%282x%5E2-expr%282%2F3%29x%5E3%29matrix%283%2C1%2C%22%7C%22%2C%22%7C%22%2C%22%7C%22%29matrix%283%2C1%2C%222%22%2C%22%22%2C%220%22%29%22%22=%22%22

%22%22=%22%22c%2A%282%284%29-expr%282%2F3%29%288%29%29%22%22=%22%22

c%2A%288-16%2F3%29%22%22=%22%22c%2A%2824%2F3-16%2F3%29%22%22=%22%22expr%288%2F3%29%2Ac

We set 

expr%288%2F3%29%2Ac%22%22=%22%221

c%22%22=%22%223%2F8

b) Find P(0.5 < X ≤ 1.5)

Now that we know c = 3/8, we want to find the shaded area below



int%28%28expr%283%2F8%29%284x-2x%5E2%29%5E%22%22%29%2Cdx%2C0.5%2C1.5%29%22%22=%22%22expr%283%2F8%29%2Aint%28%284x-2x%5E2%29%5E%22%22%2Cdx%2C0.5%2C1.5%29%22%22=%22%22expr%283%2F8%29%2A%282x%5E2-expr%283%2F8%29x%5E3%29matrix%283%2C1%2C%22%7C%22%2C%22%7C%22%2C%22%7C%22%29matrix%283%2C1%2C%221.5%22%2C%22%22%2C%220.5%22%29%22%22=%22%22

%22%22=%22%220.6875

Edwin