Directions: Study the following questions carefully and answer the questions given below.
1
The average annual income (in Rs.) of certain agricultural workers is P and that of other workers is Q . The number of agricultural workers is 9 times that of other workers. Then the average monthly income (in Rs.) of all the workers is :
» Explain it
D
Let the number of other workers be x.

Then, number of agricultural workers = 9x.

Total number of workers = 9x + x = 10x.

So, Average monthaly income
 
=   P x (9x) + Q x (x)   =  x[9P + Q ]
10x 10x
 
  = (9P + Q)
10

2
A family consist of grandparents, parents and two grandchildren. The average age of the grandparents is 56 years, that of the parents is 27 years and that of the grandchildren is 7 years. What is the average of the family?
» Explain it
C
First, we find out the normal ages of candidates:

Grand parents(2 candidates) = 56 x 2

Parents (2 candidates) = 27 x 2

Two grandchildren = 7 x 2.

The total candidates are 6. then,

Average =  56 x 2 + 27 x 2 + 7 x 2  ⇒  112 + 54 + 14
2 + 2 + 2 6

180   = 30 years
6

3
A library has an average of 430 visitors on Sundays and 270 on other days. The around average of the number of visitors per day in a month of 31 days beginning with a Saturday is:
» Explain it
D

Since the month begins with a saturady , So there will be five sundays in the month,

Req. Avg. =  430 x 5 + 270 x 26   2150 + 7020
31 31

   9170   =   295.80  296.
6

So, the arround value of vistiors per day is 296.        

4
If the average marks of three batches of 40, 50 and 60 students respectively is  30, 50 and 70, then the average marks of all the students is:
» Explain it
B
Req Avg =  40 x 30 + 50 x 50 + 60 x 70
30 + 50+ 70

 ⇒  1200 + 2500 + 4200
150

7900   = 52.66
150

Hence, option (B) is correct.

5
The average weight of 18 boys in a class is 45.55 kgs and that of the remaining 4 boys is 35.25 kgs. Find the average weight of all the boys in the class.
» Explain it
C
Reqd Avg =  18 x 45.55 + 4 x 35.25  ⇒  819.9 + 141
18 + 4 22

   960.9    =   43.67 kgs
22

Hence, option (C) is correct.