EXERCISE 8.2.
1). Convert the given fraction to per cent .
a) 1/8 = 1/8 × 100 = 12.5 %
b) 5/4 = 5/4 × 100 = 125 %
c) 3/40 = 3/40 × 100 = 70 %
d) 2/7 = 2/7 × 100 =28.6 %
2. Convert the given decimal into percent
a) 0.65 = 65/100 × 100 = 65%
b) 2.1 = 21/10= 21/10 × 100= 210%
c) 0.02 = 2/100= 2/100 ×100= 2%
d) 12 .35 = 1235/100= 1235/100 × 100= 1235%
3). Estimate what part of the figures is coloured hence find the per cent which is coloured.
i)
ii)
iii)
Ans: (i) Part of the figure coloured = 1/4
Then its per cent = 1/4 x 100 = 25%
ii) Part of the figure coloured = 3/5
then its per cent = 3/5 × 100 = 60%
ii) Part of the figure coloured = 3/5
then its per cent = 3/8 × 100 = 37.5%
4). Find
a) 15 % of 250
Ans: = 15/100 × 250= 15/10 × 25 = 75/2
b) 1 % of 1 hour
Ans: 1 hour = 60 minutes
60 minutes = 60 seconds
so 60 minutes = 60 × 60 = 3600 seconds = 37.5
1% of 3600 seconds = 1/100 × 3600= 36 seconds
c) 20% of Rs 2500
Ans: = 20/100 × 2500 = 20 × 25 = Rs 500
d) 75 % of 1 kg
Ans: 1 kg = 1000 g = 75/100 × 1000 = 750 g
5). Find the whole quantity if
5 % of it is 600
Ans: let the whole quantity be x
So, 5/100 × x = 600 x ⇒ (600 × 100)/5 x = 12000
b) 12% of it is ₹ 1080
Ans: let the whole quantity be x So, = 12/100 × x = 1080
= ( 1080 × 100)/12 = 180 × 50 x = ₹ 9000
c) 40% of it is 500 Km
Ans: let whole quantity be x So, 40/100 × x = 500
x = ( 500 × 100)/40 = 250 × 5= 1250 km
d) 70 % of it is 14 minutes
Ans: let the whole quantity be x So, 70/100 × x =14 ⇒ x = (14× 100)/70
x = 2 ×10 ⇒ x = 20 minutes
e) 8% of it is 40 litres
Ans: let the whole quantity be x
S0, 8/100 × x = 40 ⇒ x = ( 40 × 100)/8
x = 5 × 100 x = 500 litres
6). Convert given percent to decimal fraction and also to fractions in simplest form
a) 25% = 25/100= (1 )/4 = 0.25
b) 150% = 150/100 = 3/(2 ) = 1.5
c) 20 % = 20/100 = (1 )/5 = 0.2
d) 5% = 5/100 = 1/20 = 0.05
7). In a city , 30 % are females , 40 % are males and remaining are children . what per cent are children?
Ans: Percentage of females = 30 % and percentage of males = 40 %
Total percentage of both females and male = 30 % + 40% = 70%
The percentage of children = 100 − 70
= 100 − 70 = 30 %
8). Out of 15,000 voters in a constituency, 60% voted find the percentage of voters who did not vote.
Can now find how many actually did not vote?
Ans: Percentage of those who voted = 60%
Percentage of those who did not vote = 100 – 60 = 40%
Total number of voters = 15,000
Number of voters who did not vote = 40% of 15,000
= 40/100 × 15,000 = 40 × 150 = 6000
∴ 6000 voters did not vote.
9). Meeta saves ₹ 400 from her salary if this is 10% of her salary what is her salary ?
Ans: = Let Meeta’s salary be x
10% of her salary is Rs 400
So, 10/100 × x = 400
x = 400 × 100/10 = 4000
∴ Meeta’s salary is ₹ 4000.
10). A local cricket team played 20 matches in season. If they won 25% of them . how many matches did they win ?
Ans: Total matches played = 20
Percentage of matches won = 25%
Number of matches won by the team = 25% of 20
= 25/100 × 20 = 5
∴ The cricket team won total 5 matches