# Expected frequencies

1. Mar 17, 2009

### ongfufu

I need help on question 2 and 3. For question 2, I think I got the expectation for Poisson distribution, but I have no idea how to get the normal one. Could someone provide me a formula or something? Thanks a lot!

Last edited: Mar 17, 2009
2. Mar 18, 2009

### John Creighto

Once you have the PDF (Probability distiribution (normal in your case)), you integrate the PDF between the range of each bin and multiply it by 1000. You probably have tables for this in your text. One way you could get the PDF is from the mean and variance.

3. Mar 18, 2009

### ongfufu

I think the expectation for Poisson is the mean for this. So how would I get the variance? I know its the sum of the square of the possible values multiplied by the probabilities, subtract the mean squared. But what are the possible values and the probabilities?

Last edited: Mar 18, 2009
4. Mar 18, 2009