# Mathematical Expectation

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• Oct 14th 2012, 02:48 PM
Hal2001
Mathematical Expectation
Attachment 25227

I have the above conditions, the book wants me to find the value of c such that E(c^X)=1.

So I tried c^X*p+(1-p)c^X=1, which becomes,

c*p+(1-p)/c=1. From there I got the equation c^2p-c-p=-1. But I'm stuck, and I think may have went off track somewhere.
• Oct 14th 2012, 03:06 PM
Plato
Re: Mathematical Expectation
Quote:

Originally Posted by Hal2001
Attachment 25227
I have the above conditions, the book wants me to find the value of c such that E(c^X)=1.
So I tried c^X*p+(1-p)c^X=1, which becomes,
c*p+(1-p)/c=1. From there I got the equation c^2p-c-p=-1. But I'm stuck, and I think may have went off track somewhere.

No, you are correct. Just solve that quadratic equation for c.
Can you solve $px^2-x+1-p=0$
• Oct 14th 2012, 03:14 PM
Hal2001
Re: Mathematical Expectation
Oh silly me, I didn't think of considering 1-p and setting it equal to zero. Thanks.