# Math Help - pivotal quantity

1. ## pivotal quantity

Suppose X is a random variable with pdf fx(x)=2(θ-x)/θ^2 ,0<x<1?

a) Show that fx is a pdf (probability density function).
b) Find CDF( cumulative distribution function) for x.
c) Show that Y=X/θ is a pivotal quantity.
d) Find a 90% confidence interval for θ.

2. Originally Posted by lavender87
Suppose X is a random variable with pdf fx(x)=2(θ-x)/θ^2 ,0<x<1?

a) Show that fx is a pdf (probability density function).
b) Find CDF( cumulative distribution function) for x.
c) Show that Y=X/θ is a pivotal quantity.
d) Find a 90% confidence interval for θ.
What have you tried here? Where are you stuck?