A function f(x) is designed as to be a valid probability density function the value of A must be
f(x)=⎧⎪
⎪
⎪⎨⎪
⎪
⎪⎩0;x<31A(3x+5) ;3<x<6. Forf(x)0;x>6
For f(x) to be probability density function = ∞∫−∞f(x)dx=1
1A∞∫−∞(3x+5)dx=1⇒1A∣∣3x22+5x∣∣63=1
A=(3262−3232)+5(6−3)
=3227+15=55.5