How do you find the inter quartile range of a graph?

Its for my maths homework, I have a graph about the heights of boys in a class,


The x axis is for the heights and goes from 120 - 170 although the line stops at 160


The y axis has the cumulative frequency, goes from 0-50 although the line does not go above 40.





I REALLY don't understand it.





What is the IQR?


Thanks in advance.|||You find the total cumulative frequency, divide by 2 to get the median's position, see how many numbers are on each side of the median, then find the median for the numbers on each side of the median. Those are the quartiles, and the IQR is the higher quartile minus the lower quartile.





Like if there were 40 total frequency, the median would be between the 20th and 21st number.So for the first 20 numbers that median (which is the lower quartile) is between the 10th and 11th number (add them and divide by 2)


while the upper quartile is between the 30th and 31st number


so find those and subtract





Wow now that I re-read this I don't know if it will help you or not - good luck