# Math Help - Unbiased Estimator

1. ## Unbiased Estimator

I have a question on unbiased estimators and im completely lost...

2. What value of c would satisfy the following:

$E(c(X_1 + 2X_2)) = \frac{1}{\theta}$

3. Originally Posted by statmajor
What value of c would satisfy the following:

$E(c(X_1 + 2X_2)) = \frac{1}{\theta}$
since they are i.i.d.

$3cE(X) = \frac{1}{\theta}$

4. Originally Posted by matheagle
since they are i.i.d.

[tex]3cE(X) = \frac{1}{\theta}[/m
ath]
Sorry but can you explain what you just did? And what is I.I.d?

5. Originally Posted by jmat
Sorry but can you explain what you just did? And what is I.I.d?
It means independent and identically distributed. From which it follows that E(X1) = E(X2). From which matheagle's equation follows. And you should know how to calculate an expected value when you have the pdf.