We have seen how percentage are used in comparison of quantities. We also learnt to convert fractions and decimals to percentage and vice-versa.

**Percentage in Real Life**

We have seen how percentage are used
in comparison of quantities. We also learnt to convert fractions and decimals to
percentage and vice-versa.

Now we shall see some situations that
use percentage in real life such as 5% of income is allotted for saving; 20% of
children’s picture book is coloured green; a book distributor gets 10% of profit
on every book sold by him. What can we conclude from these situations.

** **

__Percentage as a value__

__Example 2.14__

** **There are 50 students in a class. If 14% are absent on a particular
day, find** **the number of students present
in the class.

**Solution:**

Number of students absent on a particular
day =
14 % *of* 50

= 14/100 ×50= 7

Therefore, the number of students present
=
50 −
7 =
43 students.

__Example 2.15 __

Kuralmathi bought a raincoat
and saved ₹ 25 with discount of 20%. What** **was the original price of the raincoat?

**Solution:**

Let the price of the raincoat (in ₹ )
be *P*. So 20% of *P* = 25

(20/100) × *P* = 25

P = (25 ×100) /20 = 125

Therefore, the original price of the
raincoat is ₹ 125.

__Example 2.16 __

An alloy contains 26 % of
copper. What quantity of alloy is required to get** **260 g of copper ?

**Solution:**

Let the quantity of alloy required be
Q *g*

Then 26 % of Q =260 *g*

[26/100] ×
Q = 260 g

260/100 × Q = 260
g

Q = (260 × 100) / 26 g

Q = 26000
/ 26 g

Q = 1000 g

Therefore, the required quantity of alloy
is 1000 *g.*

** **

__Ratios as percentage__

Sometimes ingredients used to prepare
food can be represented in the form of ratio. Let us see some examples.

__Example 2.17 __

Kuzhal’s mother makes dosa
by mixing the batter made from 1 portion of** **Urad dhal with 4 portions of rice. Represent each of the ingredients
used in the batter as percentage.

**Solution:**

Representing ingredients used in the
batter as ratio, we get, rice : urad dhall = 4 : 1

Now, the total number of parts is 4 +
1 =
5 .

That is, 4/5 portion of rice is mixed
with 1/5 portion of urad dhall.

Thus, the percentage of rice would be 4/5 ×100%
= 400/5 %= 80%

The percentage of urad dhall would be
1/50 ×100% = 100/5 %= 20%

__Example 2.18 __

A family cleans a house for
pongal celebration by dividing the work in the** **ratio 1:2:3. Express each portion of work as percentage.

**Solution:**

The total
number of parts of the work is 1 + 2 + 3 = 6

That is, the
work is divided into 3 portions as 1//6,2/6 and 3/6.

Thus, the percentage of 1/6 ^{th} portion
of work would be 1/6 ×100% = 100/6 %=16 (2/3) %

Similarly, the percentage of 2/6 ^{th }portion
of work would be 1/2 × 100% = 200/6 %= 33 (1/3) %

Similarly,
the percentage of 3/6 *th* portion of work would be 3/6 ×
100% =
300/6 % =
50%

** **

__Increase or decrease as Percentage__

There are situations where we need to
know the increase or decrease of a certain quantity as percentage. Let us see few
examples.

__Example 2.19 __

During Aadi sale the price
of shirt decreased from ₹ 90 to ₹ 50. What is the** **percentage of decrease.

**Solution:**

Original price
= the price of the shirt before Aadi month

Amount of
change = the decrease in the price = 90 – 50 = ₹ 40

Therefore,
the percentage of decrease = [ Amount of change / Original amount ] ×100

= 40/90 ×100 = 400/9

= 44 (4/9) %

__Example 2.20 __

The number of literate persons
in a city increased from 5 lakhs to 8 lakhs** **in 5 years. What is the percentage of increase?

**Solution:**

Original amount
= the number of literate persons initially = 5 lakhs

Amount of
change = increase in the number of literate persons = 8 – 5 = 3 lakhs

Therefore,
the percentage of increase = ( Amount of
change/ Original amount ) ×100

= 3/5 ×100 = 60%

**Try these**

Level of water in a tank
is increased from 35 litres to 50 litres in 2 minutes, what is the percentage of
increase?

__Profit or Loss as a Percentage__

We have learnt already profit and loss
of items. Now we will see how a profit or loss can be converted to percentage. That
is, to find the profit % or loss %, we will see some examples.

__Example 2.21 __

A shopkeeper bought a chair
for ₹ 325 and sold it for ₹ 350. Find the profit** **percentage.

**Solution:**

Profit per cent = ( Profit / C.P ) ×100

= (25/325) × 100 = 100/13 = 7 (9/13) %.

__Example 2.22 __

A T-shirt bought for ₹ 110
is sold at ₹ 90. Find the loss percentage.

**Solution:**

Cost price
of T-shirt is ₹ 110 and Selling price is ₹ 90. So, the loss is ₹ 20

Hence, for
₹ 100 the loss is 20/110 ×100 = 200×11 = 18 (2/11)% .

__Example 2.23__

** **An item was sold at ₹ 200 at a loss of 4 %. What is its cost price.

**Solution:**

To find the
cost price,

Loss per cent
= [ Loss / C.P ] ×100

4% = [ Loss
/ C.P ] ×100

4% = Loss/200
×100

Loss = 8

C.P = S.P
+ Loss

= 200+8

= 208

Hence the
cost price of the item is ₹ 208.

The world's population
is growing by 1.10 % per year.

50.4 % of the world's population is male and 49.6 % is female.

Tags : Term 3 Chapter 2 | 7th Maths , 7th Maths : Term 3 Unit 2 : Percentage and Simple Interest

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