Question

2. Find the ain themetic mean from the following
Collowing table.
Manks Cless thand to to 10 20
10 20 30 40 50 60 70 80
5 13 20 32 60 TO 90 100
No. of students​

Answer 1

Step-by-step explanation:

Following is the monthly income of eight families in a locality

Monthly Income (₹) : 70, 10, 500, 75, 13, 250, 8, 42

Find out arithmetic mean using Direct Method and Short-cut Method.

ANSWER:

Families

Monthly income

(X)

Deviation from the Assumed average

(d = X − A) (A = 75)

1

2

3

4

5

6

7

8 70

10

500

75 (A)

13

250

8

42 −5

−65

425

0

−62

175

−67

−33

(N) = 8

(ΣX)=968 Σd = −232 + 600 = 368

where,

N= Number of items

ΣX= Total of monthly income of all the families

Σd= net sum of deviations

Calculation of Mean by Direct Method

X=ΣXN=9688=121

Calculation of mean by short cut method

X=A+ΣdNor, X=75+3688or, X=75+46⇒X=121

So, mean monthly income of a family is Rs 121