Question

1. Draw a cumulative frequency curve (less than type) for the following
data and find the median from it:
Class interval 200–220 220-240 240-260 260-280 280–300 300-320
Frequency
3
2bh
4
7
6
8​

Answer 1

Explanation:

From the given table, we may prepare the 'less than' frequency table as shown below:

Class

c.f

Less than 220

7

Less than 240

10

Less than 260

16

Less than 280

24

Less than 300

26

Less than 320

30

We plot the points A(220,7), B(240,10), C(260,16), D(300,24), E(300,26) and F(320,30).

Join AB, BC, CD, DE, EF and FA with a free hand to get the curve representing the ‘less than type’ series.

Here, N=30

⇒N2=15

From P(0,15), draw PQ∥x−axis meeting the curve at Q. Draw QM⊥OX meeting x−axis at M.

Clearly, OM= 256 units

Hence, Median=256