### Comparing Quantities - Solutions

CBSE Class –VII Mathematics

NCERT Solutions

Chapter 8 Comparing Quantities (Ex. 8.1)

Question 1. Find the ratio of:

(a) Rs. 5 to 50 paise

(b) 15 kg to 210 g

(c) 9 m to 27 cm

(d) 30 days to 36 hours

Answer: To find ratios, both quantities should be in same unit.

(a) Rs. 5 to 50 paise

5 x 100 paise to 50 paise [Rs. 1 = 100 paise]

500 paise to 50 paise

Thus, the ratio is = = 10 : 1

(b) 15 kg to 210 g

15 x 1000 g to 210 g [ 1 kg = 1000 g]

15000 g to 210 g

Thus, the ratio is = = 500 : 7

(c) 9 m to 27 cm

9 x 100 cm to 27 cm [ 1 m = 100 cm]

900 cm to 27 cm

Thus, the ratio is = = 100 :3

(d) 30 days to 36 hours

30 x 24 hours to 36 hours [ 1 day = 24 hours]

720 hours to 36 hours

Thus, the ratio is = = 20 : 1

Question 2. In a computer lab, there are 3 computers for every 6 students. How many computers will be needed for 24 students?

Answer: 6 students needed = 3 computers

Therefore 1 student needs = computers

24 students needs = times 24 = 12 computers

Thus, 12 computers will be needed for 24 students.

Question 3. Population of Rajasthan = 570 lakhs and population of U.P. = 1660 lakhs. Area of Rajasthan = 3 lakh and area of U.P. = 2 lakh .

(i) How many people are there per km2 in both states?

(ii) Which state is less populated?

Answer: (i) People present per =

In Rajasthan = = 190 people per

In U.P. = = 830 people per

(ii) Rajasthan is less populated.