INTRODUCTION

Ogive curve

There are two types

Of curve

More than type

frequency curve

Less than type

frequency curve

EX 14.4 (1)The following distribution gives the daily income of 50 workers of a factory.

Convert the distribution above to a less than type cumulative frequency

distribution, and draw its ogive.

Sol.

Cumulative Frequency

Points to be plotted

100 - 120

120 - 140

140 - 160

160 - 180

180 - 200

12

14

8

6

10

12

40

50

(120,12)

(140,26)

(160,34)

(180,40)

(200,50)

14

+

12

= 26

26

+

26

8

= 34

34

less than type cumulative frequency

draw its ogive

Daily income (in Rs)

Daily income (in Rs)

Numbers of workers

Numbers of workers

Exercise 14.4 – Q.1

x'

0

y'

120

140

160

180

200

x

5

10

15

20

25

30

35

40

45

50

Daily income (in Rs)

No. of workers

Scale : X-axis, 1cm =Rs.10

Y-axis, 1cm = 5 workers

(120,12)

(140,26)

(160,34)

(180,40)

(200,50)

y

Now let us plot the points on a graph

20

20

20

20

120

Points to be plotted

(120,12)

(140,26)

(160,34)

(180,40)

(200,50)

Leaving 2 cm from bottom we draw horizontal X-axis and leaving 2cm from left we draw vertical Y-axis

On X-axis if classes are not starting from ‘0’ leaving 2cm from X-axis we start putting limits .

Looking at the biggest Y-co ordinate we select the scale on Y - axis

We plot the points one after the other and write the co-ordinate

Join all points with smooth curve

The difference between origin and lower limit of first class is not same as the width of classes hence we put a Krink mark

Exercise 14.4 – Q.1