Thread: Normal Distribution question

Hey, new on here so i'm not exactly sure how this works but i've got this question i feel like i should be able to do but i'm just not quite sure how to approach it:

A factory produces cylinders that are to be put inside pipes. The diameter of the cylinders are IID Normal with mean 10cm and variance 4cm^2. The diameter of the pipes are IID Normal with mean 12cm and standard deviation 1cm. If we select 100 pairs of cylinders and pipes at random, what is the expected number of pairs for which we will not be able to fit the cylinder in the pipe?

I've attached the question along with the parts that came before it which could be clues and the answers are shown but just as a number but it's the method i'm stuck on.

Thanks for your help

Jake

I answered a question similar to this yesterday. I hope this gives you the right hint.

http://www.mathhelpforum.com/math-he...tml#post492451

Hi, just noticed after I posted it. I was just being really stupid and forgetting to square the variance, definitely won't do that again!!

Thanks for your help.