O Level Maths Help! How do you work out the median on a cumlative frequency curve?

Answer 1

Let's say you are plotting a cumulative frequency of (say) height for a group of 100 people. You might plot it on a graph with number of people up the Y axis and height along the X axis. Once you have the curve you look on the Y axis for the 50 mark (half the people) and move across horizontally onto the curve, then vertically down to the X axis. The figure there is the median. It is the height that half the people are less than and half the people are more than - ie the height in the middle (median) of the population.

Answer 2

To work out the median on acumulative frequency graph : assume u have a curve, to get the median= total of numbers/2 e.g. 2,3,5,2,7,4,8,3,6
Median= rearrange in ascending order
=2,2,3,3,4,5,6,7,8
=4 is the median
To get it add all the numbers, and divide the sum by 2. With the above, it 'll be 2+2+3+3+4+5+6+7+8 = 40/2 =20th number
on the graph, trace the 20th number, and down to get the median number required.

Answer 3

oooo I know!
you take your cumulative frequency curve, and at the middle frequency (i.e. the median cumulative frequency on the y axis) and draw a horizontal straight line until it touches the cumulative frequency curve. then you draw a straight line down from the intersection so that it touches the x axis. where it touches the x axis is the median of a cumulative frequency curve.
if you also want to find the upper and lower quartiles, you can do the same, but half of the median up and down.

Answer 4

draw a straight line from half way of your cumulative frequency axis to the curve. Then go 90 degrees when u hit the curve to read the value at this point. You can work out quartiles in a similair way.

Answer 5

USE HALF OF THE MAXIMUM FREQUECY VALUE AND reda the corresponding value of the x axis

Answer 6

lol what