I have the question:

Explain why a discrete uniform random variable, X, on [a,b] has the same variance as a discrete uniform random variable, W, on [1,b-a+1].

Use this information to establish that

http://thestudentroom.co.uk/latexren...93ea8adc71.png

...I don't even know where to start http://static.thestudentroom.co.uk/i...onal/frown.gif so any help would be great cheers