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# S2 Watch

1. well i know f(x) = 1/2
E(r) =7 and var(R)=1/3
but i need E(c) and Var(C), what do i do next!
2. (Original post by Ayaz789)
well i know f(x) = 1/2
E(r) =7 and var(R)=1/3
but i need E(c) and Var(C), what do i do next!
Circumference is 2pi * R.

P(C < 45) = P(2pi * R < 45) = P(R < 45/2pi) = P(R< 7.16) which is an easy rectangle area.
3. (Original post by Zacken)
Circumference is 2pi * R.

P(C < 45) = P(2pi * R < 45) = P(R < 45/2pi) = P(R< 7.16) which is an easy rectangle area.
Okay ill have a go again at both part i and ii and ill come back!

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