SOLUTION: Let X be a random variable with probability density function given by:           | 0, if x <0 f (x) = { cx, if 0 <= x <= 2           | 0, if x> 2 a) Get the value of consta

Algebra ->  Probability-and-statistics -> SOLUTION: Let X be a random variable with probability density function given by:           | 0, if x <0 f (x) = { cx, if 0 <= x <= 2           | 0, if x> 2 a) Get the value of consta      Log On


   



Question 1105410: Let X be a random variable with probability density function given by:
          | 0, if x <0
f (x) = { cx, if 0 <= x <= 2
          | 0, if x> 2
a) Get the value of constant c.
b) Get the cumulative distribution function F (x).
c) Get P (1/4 < X <3/4).

Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!


a) Get the value of constant c.
Since f(2) = c(2) = 2c

f(x) has the graph:



Since this is a probability density function, the area between
the graph (in red) and the x-axis is 1.  Since the entire area 
is the area of the right triangle, we just use the formula for 
the area of a triangle:

 
So since the area A of the triangle is 1, 

 

matrix%281%2C3%2C1%2C%22%22=%22%22%2C2c%29

matrix%281%2C3%2C1%2F2%2C%22%22=%22%22%2Cc%29

And therefore



So the point (2,2c) is the point (2,1), 
and the graph of f(x) is



b) Get the cumulative distribution function F (x).


c) Get P (1/4 < X <3/4).
F%283%2F4%29-F%281%2F4%29%22%22=%22%22F%280.75%29-F%280.25%29%22%22=%22%22%280.75%29%5E2%2F4%5E%22%22-%280.25%29%5E2%2F4%5E%22%22%22%22=%22%220.125%22%22=%22%221%2F8

Edwin