Please I want to know the answer of:

a discrete random variable X has probability function
px(x)=2ֿx (this means 2 to the power of -x), x=1,2,3,.

Calculate:
a) Pr(X is even)
b)Pr(x>5)
c)Pr(X is divisible by 3)

Thanks a lot

Integration.

If x is even, then it must be divisible by 2. Right?

P(\text{x is even})=\int_{1}^{\infty}2^{-2x}dx=\int_{1}^{\infty}\frac{1}{2^{2x}}dx=\int_{1} ^{\infty}\frac{1}{4^{x}}dx


Try the others and let me know if you get stuck. See how to set up the third one now using this idea. How about #2?

Sorry but I didn't understand :(

Then you best see your instructor.