Math Is Fun Forum

jubadedo

Member

Registered: 2015-04-05

Posts: 19

Expectation Questions (Probability)

1. If E[X] = 2 and var(X) = 3, what is E[(X + 1)2]?

2. If E[X] = 2 and var(X) = 3, what is var(3X + 2)?

3. Let X be a Bernoulli random variable with p=.25.  Find E[4X5-1].

Hi guys, thank you so much for helping me out throughout this year. I really appreciate it! I am confused with how to solve these problems. If anyone could provide assistance, I would really appreciate it. Thanks so much!

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Expectation Questions (Probability)

Hi;

For 3) as far as I remember if you meant E[4X^5-1] when X is a Bernoulli Random variable with p being the probability.

So just substitute p = 1 / 4

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

jubadedo

Member

Registered: 2015-04-05

Posts: 19

Re: Expectation Questions (Probability)

So 3 is just 0? Whoa

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Expectation Questions (Probability)

That is what I am getting.

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.