1) This document contains examples of calculating averages and percentages. It provides 7 problems with step-by-step solutions for finding averages of data sets, natural numbers, ages based on ratios, and determining an unknown value based on average. 2) The last problem asks to determine the age of C after 8 years if 4 years ago the average of A and B was 18 and currently the average of A, B, and C is 24. 3) Calculating percentages is also mentioned as a topic covered but no specific examples are given.

1. UNIT-2
AVERAGE
PERCENTAGE
PROFIT AND LOSS

2. 1) Average=
2) Suppose a man covers a distance at x kmph and an equal
distance at y kmph then Average speed during the whole journey
=

3. PROBLEMS:
1) Find the average of the follwing set of
numbers
354,281,623,518,447,702,876
Ans:543
2)There are 6numbers 30,72,53,68,x and
87 out of which x is unknown.The
average of numbers is 60.What is the
value of x
ans:x=50
3)Find the average of first 40 natural
numbers
Ans: sum of n natural numbers =n(n+1)/2

4. Average =820/40=20.5
4)Find the average of the first 20 multiples
of 7
Ans: multiples of 7
7,14,21……………………..140
7(1+2+3+………………20)
Average = 7(1+2+3+………………20)/20
=7(20x21)/2)/20
=7(20x21/2x20)
=147/2=
5)The average of the 5 consecutive
numbers A,B,C,D,E is 48.What is the
product of A andE

5. Let the numbers A,B,C,D,E,
are x,x+1,x+2,x+3,x+4
5x+10/5=48
X=46

6. 6). How much will be the average of
the squares of natural numbers
from 1 to 40?
verage of squares
of first 'n' natural
numbers
=
(n+1)(2n+1)
6
Average of
squares of
first 'n'
natural
numbers
=
(n+1)(2n+1)
6

7. Avera
ge of
squar
es of
numb
ers
from 1
to 40
=
(40+1)
(80+1)
=
41 x 81
= 553.5
6 6

8. 7) The average age of a man and his son is
40 yrs .The ratio of their age is 11:5
.What is the son ‘s age
Ans: let the age of man and his son be
11x and 5x
average age =11x+5x /2=8x
8 x=40
X=5
Sn
son’s age =5x5=25 yrs.

9. 7) The average age of a man and his son is
40 yrs .The ratio of their age is 11:5
.What is the son ‘s age
Ans: let the age of man and his son be
11x and 5x
average age =11x+5x /2=8x
8 x=40
X=5
Sn
son’s age =5x5=25 yrs.

10. 7) The average age of a man and his son is
40 yrs .The ratio of their age is 11:5
.What is the son ‘s age
Ans: let the age of man and his son be
11x and 5x
average age =11x+5x /2=8x
8 x=40
X=5
Sn
son’s age =5x5=25 yrs.

11. 8)Four years ago the average age of A and
B was 18 years.At present the average
age of A,B,C is 24. What would be the
age of ‘C’ after 8 years?
Ans: 36

12. PERCENTAGES