stats:find the mean
posted by sha .
please help! i know exactly how to find the mean but i am having a problem finding the midpoints. couldn't get them right :(
salary employees
5,001 10,000 == 16
10,00115,000 == 15
1500120,000 == 11
20,00125,000 == 15
25,00130,000 == 23

If you want the mean salary, you can only get an approximate value since you only have histogram data (the number per salary interval). Assume that the number 16 applies to a salary at the midpioit of the first interval ($7500), etc.
The mean will be
(16*7500 + 15*12500 + 11*(17,500) + 15*22500 + 23*27,500)/(16+15+11+15+23) = $18,375 
thanks a bunch!! =D