In the table here we can see that ages of people are given from 0 to 10 10 to 20 up to 50 to 60 this letter. A stands there ages, also number of children that belong to each age group that is from 0 to 10. There are 9 people 10 to 20. There are 12 people. And so on. This column is what we call this frequency. So to begin with this sum, we need to make another column called the cumulative frequency column.
Let me show you what cumulative frequency means cumulative frequency is the total of all frequencies. Up to a particular point, so let's say that the cumulative frequency for 0 to 10 is 9. And when we move to 10 to 20, it becomes 9 plus 12 is equal to 21. That is the total of all frequencies from 0 to 20. This keeps going on.
So we get 21 plus 3 is equal to 24 for the next CF and 24, plus 14 is equal to 38 for the next. And then we get 50 and 60 as the CF for the last 2. Now, as you notice in the ages' column, I have marked the lower class boundaries and higher class boundaries on the give. We have to mark. Higher class boundaries, only on the x-axis and the CF on the y-axis, let me show you how that is done on a graph, draw your x-axis and y-axis and mark, the ages say, 0, 10, 20, 30, 40 50 60 on the x-axis and CF that is also starting from 0 and going up to 10 20 30, 40 50 60. The next step is to plot these points on a graph. So 10 on the x-axis corresponds to 9 on the y-axis that is in the CF column.
You must mark 9 just a little below 10 on the y-axis. Then we start marking 20 on the x-axis, 21 on the y-axis. And then 30 24, 40, 38, 50 50. And the last one is 60 60. This is how we get our points on the graph. Then we join all the points and our give is ready now to find the median, which is the midpoint of the data given we will first need to find the midpoint of the CF, which is 60 upon 2.
That is the 30th term should be the median. Now, as you can see, we draw a line from 30 on the y-axis to the give and then drop a perpendicular from the give to the x-axis, the point at which the line meets. The x-axis is 35. Which is your median, I hope, you liked the video, please, tell your friends to watch this. If you liked it all the best.