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# Probability - IRV's watch

1. Hi, I've been given a problem and am struggling to get started as I don't know what lower case z represents. If you could take a look it would be much appreciated.

Thanks
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2. (Original post by Substitution)
Hi, I've been given a problem and am struggling to get started as I don't know what lower case z represents. If you could take a look it would be much appreciated.

Thanks
is just an arbitrary number in .

3. Not sure where to go with the problem from here. I've attached my workings, thanks!
4. (Original post by Substitution)

Not sure where to go with the problem from here. I've attached my workings, thanks!
Since your pdf is 0 everywhere except for then integrating from is the same as integrating from .
5. (Original post by Substitution)

Not sure where to go with the problem from here. I've attached my workings, thanks!
You've got the fact that P(Y <= z) = P(X <= z, Y <= z). But you are given the fact that X and Y are independent, so you can simplify the right hand side immediately without any thought of integrals. Then express this simplification in terms of cumulative distribution functions.

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