Page 104 - ICSE Math 7

MENTAL MATHS

1. Choose the correct answer.

(a) What is the ratio of 60 kg to 6,000 g?
(i) 60 : 1 (ii) 10 : 1 (iii) 1 : 10 (iv) 1 : 6
(b) Which of the following are in proportion?
(i) 2, 3, 5, 6 (ii) 1, 3, 2, 5 (iii) 1, 3, 4, 12 (iv) 6, 3, 4, 7

(c) If 12 : 24 = 72 : x, what is the value of x?
(i) 148 (ii) 124 (iii) 120 (iv) 144
(d) What is the simplest form of the ratio 35 : 120?
(i) 7 : 24 (ii) 5 : 20 (iii) 7 : 12 (iv) 9 : 24

2. Write True or False.
(a) The ratio between 10 kg and 100 kg is 1 : 10.
(b) The value of a ratio does not change if both the terms are multiplied by the same non-zero
number.
(c) If a : b = 9 : 7 and b : c = 7 : 61, then a, b, c are in continued ratio.
1
(d) If a man takes 17 days to complete a work, then the work done by him in 1 day is .
17
(e) If increase in one quantity causes decrease in the other quantity, then the two quantities are
in direct variation.

3. Fill in the blanks.
(a) If the cost of 4 eggs is ` 20, then the cost of 1 egg is ` ________.

(b) If 18 men can do a piece of work in 2 days, then 1 man can do the same work in _______
days.
(c) If the cloth required for 1 shirt is 1.5 m, then the cloth required for 4 shirts is _________ m.
(d) For 8 days, Seema requires ` 6,400. So, for 4 days, she requires ` __________.

PRACTICE TIME

1 1
1. Amit studies for 8 hours and plays for 3 hours every day. Find the ratio of the time he studies
2
2
to the time he plays.
2. The length of a rectangular piece of cloth is 168 cm. If the ratio of the length to the breadth of
the cloth is 7 : 3, then find the breadth of the cloth.
3. Distribute 160 candies between A and B such that A has thrice as much as B.
4. Find the multiplying ratio which changes 115 kg to 150 kg.
1 1 1
5. The sum of weights of three bags is 370 kg. If the ratio of their weights is 6 : 2 : 3 , find
3
2
2
their weights.
6. Two numbers are in the ratio 8 : 11. If the difference between the numbers is 111, find the numbers.
7. The ages of two friends are 5 years 6 months and 6 years. Divide 207 marbles between them in
the ratio of their ages.

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