Page 86 - Maths Skills - 7

84 Maths

Example 5: Which is the greatest ratio: 2 : 3, 3 : 5, 4 : 7 Example 6: Find the value of ‘x’ in the given
or 7 : 8? proportion: 8 : x :: 32 : 40.

2 Solution: 8 : x :: 32 : 40
Solution: 2 : 3 = = 0.67 8 32
3
3 ⇒ = 40
x
3 : 5 = = 0.6 40 × 8
5
4 ⇒ x = 32 = 10
4 : 7 = = 0.57 4
7
7 ⇒ x = 10
7 : 8 = = 0.87
8
Hence, 7 : 8 is the greatest ratio.

Exercise 5.1

1. Find the ratio of the following.

(i) 1 crore to 1 million (ii) 50 paise to ` 3 (iii) 60 minutes to 35 seconds
(iv) 16 hrs to 2 days (v) 160 cm to 1 metre (vi) 6 km to 150 m
(vii) 7 kg to 140 g (viii) 1.5 L to 2.7 L (ix) 7.35 to 10.95

(x) 2 m to 5 m

2. Mr. Chatterjee divides a sum of ` 1,200, as gifts for his two sons, in the ratio 5 : 3. How much does
each child get?
3. A distance of 700 km between two cities A and B is represented in the map by 5 cm. What is the distance
between the two cities A and C if they are 11 cm apart in the map?
4. On World Environment Day, students of School A planted 615 plants whereas students of School B
planted rest of the plants. If total number of plants were 1050, find the ratio of plants of School A to
School B.
5. A jet plane requires 600 kg of fuel in 45 minutes. How much fuel would be used for a two hours flight?

6. In a school, for every 50 raffle tickets sold, the student receive ` 500. If a student receives ` 1,500, how
many raffle tickets are sold by him?

7. If a, b, c are in proportion. Find ‘a’ if b = 15 and c = 40.
8. In a school, 9 out of 40 students of Class VII A got ‘A’ grade and 6 out of 30 students of Class VII B got
‘A’ grade. Which section of Class VII has better record of ‘A’ grades?
9. Which ratio is greater?

(i) 2 : 5 or 3 : 7 (ii) 4 : 5 or 5 : 6 (iii) 6 : 11 or 9 : 14 (iv) 1 : 4 or 6 : 30
10. At 11 a.m., a two-metre high pole gives a shadow of 2.5 m. A tall tree in the same area at the same time
gives a shadow of 17.5 m. What is the height of the tree?

11. 50 kg of sweets can be served to 200 people. How much sweet is required for 700 people?
12. Find the value of ‘x’ in the following.

(i) 4 : x : : 20 : 35 (ii) 2.5 : 7.5 : : x : 10.5 (iii) x : 19 : : 142 : 71 (iv) 21 : 35 : : 33 : x