# Resolved: Histogram exercise and solution

In exercise sheet, absolute frequency formulas are like this:

=COUNTIF($B$11:$B$30,">="&D16)-COUNTIF($B$11:$B$30,">"&E16)

However, in solution sheet, like this.

=COUNTIFS($B$11:$B$30,">="&D16,$B$11:$B$30,"<="&E16)

The formula in the solution part is understandable, quite normal. However, I did not understand the one in the exercise sheet. How is it possible to get the right answer? What does the minus between to Countif formula mean? Why ">"&E16 but not "<"&E16 or "<="&E16 ?

when we count all numbers > 21, formula will count numbers greater than 21 (first), then when we count all numbers > 41 formula will count numbers greater than 41(second).

when we Subtract numbers greater than 41(second) from numbers greater than 21 (first), we will get the numbers between 21 and 41

EX

from 2 to 7- from 4 to 7= from 2 to 4

2,3,4,5,6 - 4,5,6 = 2,3