# Question about expected frequencies within ranges

1. Mar 7, 2012

### chuy52506

Say I have ranges:
(-infinity to 16) where the observed frequency is 35
(16 to 18) where the obs freq is 100
(18 to 20) where the obs.. freq. is 360
(20 to 22) where the obs. freq. is 326
(22 to 24) where the obs. freq. is 150
(24 to infinity) where the obs freq is 29

The mean is 20 and standard deviation is 2

How would i find the expected value of each range?

2. Mar 7, 2012

### chuy52506

anyone have an idea on how to do this?

3. Mar 7, 2012

### chuy52506

i meant to ask how to find the expected frequency not value? sorry

4. Mar 7, 2012

### mathman

I saw your post on a previous forum - there is no good answer.

5. Mar 7, 2012

### chuy52506

yes its possible. I have done it before but forgot the method I used. I was hoping someone knew how to do it.

6. Mar 7, 2012

### HallsofIvy

If all you know is that there are 100 observations between 16 and 18, but do not know where they they lie, you can't calculate an expected value.