Question

For data given in the adjoining table, the mean is:

C.I.	f	x
0-10	5
10-20	10
20-30	10

विकल्प

• 17

• 27

• 25

• 60

Answer 1

17

Explanation:

In the table,

x is the mean value or class mark,

i = class-size = 10,

C.I.	f	x	u = (x - A)/i	f × u
0-10	5	5	(5 − 15)/10 = −10/10 = −1	−5
10-20	10	A = 15	(15 − 15)/10 = 0/10 = 0	0
20-30	10	25	(25 − 15)/10 = 10/10 = 1	10
Total	Σf = 25			Σfu = 5

By formula,

\[\text{Mean} = A + \frac{\Sigma fu}{\Sigma f} \times i\]

Substituting values we get:

\[\text{Mean} = 15 + \frac{5}{25} \times 10 = 15 + \frac{50}{25} = 15 + 2 = 17.\]