## NCERT Solutions – Comparing Quantities Ex 8.2

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### Ex 8.2 Class 7 Maths Question 1.

Convert the given fractional numbers to per cents:

Solution:

### Ex 8.2 Class 7 Maths Question 2.

Convert the given decimal fractions to per cents:

(а) 0.65

(b) 2.1

(c) 0.02

(d) 12.35

Solution:

(a) 0.65 = \(\frac{0.65 \times 100}{100}\) = 0.65 × 100% = 65%

(b) 2.1 = \(\frac{2.1 \times 100}{100}\) = 2.1 ×100% = 210%

(c) 0.02 = \(\frac{0.02 \times 100}{100}\) = 0.02 × 100% = 2%

(d) 12.35 = \(\frac{12.35 \times 100}{100}\) = 12.35 × 100% = 1235%

### Ex 8.2 Class 7 Maths Question 3.

Estimate what part of the figures is coloured and hence find the per cent which is coloured.

Solution:

(i) Fraction of coloured part = \(\frac{1}{4}\)

∴ Percentage of coloured parts 100

(ii) Fraction of coloured part = \(\frac{3}{6}\)

∴ Percentage of coloured parts

(iii) Fraction of coloured part = \(\frac{6}{8}\)

∴ Percentage of coloured parts

### Ex 8.2 Class 7 Maths Question 4.

Find:

(a) 15% of 250

(b) 1% of 1 hour

(c) 20% of ₹ 2500

(d) 75% of 1 kg

Solution:

(a) 15% of 250 = \(\frac{15}{100} \times 250=\frac{75}{2}=37.5\)

(b) 1% of 1 hour = 1% of 60 minutes [∵ 1 h = 60 min.]

### Ex 8.2 Class 7 Maths Question 5.

Find the whole quantity if

(a) 5% of it is 600

(b) 12% of it is? 1080

(c) 40% of it is 500 km

(d) 70% of it is 14 minutes

(e) 8% of it is 40 litres

Solution:

Let the required whole quantity be x.

(a) 5% of x = 600

Thus the required whole quantity is 12,000.

(b) 12% of x = ₹ 1080

Thus, the required quantity is ₹ 9,000.

(c) 40% of x = 500 km

Thus, the required quantity = 1250 km.

(d) 70% of x = 14 minutes

Thus, the required quantity = 20 minutes,

(e) 8% of x = 40 litre 8

Thus, the required quantity = 500 litres

### Ex 8.2 Class 7 Maths Question 6.

Convert given per cents to decimal fractions and also to fractions in simplest forms:

(a) 25%

(b) 150%

(c) 20%

(d) 5%

Solution:

### Ex 8.2 Class 7 Maths Question 7.

In a city, 30% are females, 40% are males and remaining are children. What per cent are children?

Solution:

Given: 30% are females

40% are males

Total Percentage of females and males

= 30% + 40% = 70%

∴ Percentage of children

= (100 – 70)% = 30%

### Ex 8.2 Class 7 Maths Question 8.

Out of 15,000 voters in a constituency, 60% voted. Find the Percentage of voters who did not vote. Can you now find how many actually did not vote?

Solution:

Total number of voters = 15,000

Percentage of the voters who voted = 60%

∴ Percentage of the voters who did not vote

= (100 – 60)% = 40%

Actual number of voters who did not vote

= 40% of 15,000

\(=\frac{40}{100} \times 15,000=6,000\)

### Ex 8.2 Class 7 Maths Question 9.

Meena saves ₹ 400 from her salary. If this is 10% of her salary. What is her salary?

Solution:

Let Meena’s salary by ₹ x.

∴ 10% of x = ₹ 400

Thus, her salary is ₹ 4000.

### Ex 8.2 Class 7 Maths Question 10.

A local cricket team played 20 matches in one season. It won 25% of them. How many matches did they win?

Solution:

Number of matches played by the cricket team = 20

Percentage of the matches won by them = 25%

i.e. \(\frac{25}{100} \times 20=5\) matches

Thus, the number of matches won by them = 5