Page 187 - Maths Class 06

At a Glance

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l The ratio of two quantities in the same unit is a fraction that one quantity is of the other.
l The ratio of two numbers is usually expressed in its simplest form.
l The first term of a ratio is called antecedent and the second term is called consequent.
l All equivalent ratios can be expressed as one common ratio in its lowest form.
l An equality relation between two ratios is called the proportion.
l a, b, c, d are in proportion, if a : b = c : d, where a and d are extreme terms of extremes and b, c are
middle terms or means.
l In a proportion, the product of the extreme terms equals the product of the middle terms.
l If a : b = b : c, then b² = a × c.
l Finding the unit value of something in order to calculate the value of an item for a given number of
units is called the unitary method.

Multiple Choice Questions

Tick (3) the correct answer:

1. For the ratio to be meaningful the terms should have:
(a) same units (b) same value (c) same factors (d) different units
2. The ratio of 15 minutes to 1 hour is:
(a) 15 : 1 (b) 1 : 2 (c) 1 : 4 (d) 4 : 1
3. Krish trav els 8 km in an hour. Arushi trav els 12 km in half an hour. The ratio of the speed of Krish
to the speed of Arushi is:
(a) 2 : 3 (b) 3 : 2 (c) 1 : 2 (d) 1 : 3
4. If 1, 2 3 and x are in propor tion, then the value of x is:

(a) 3 (b) 4 (c) 5 (d) 6
5. Gaurav earns ` 1,200 in 10 days. In 18 days he will earn:
(a) ` 2,160 (b) ` 2,000 (c) ` 1,960 (d) ` 2,250
6. The ratio of girls to that of boys in a class is 5 : 4. If there are 25 girls in the class, then the number
of boys is:
(a) 15 (b) 20 (c) 25 (d) 30

7. If q is the mean proportion of p and r then the value of q is:
pr
(a) pr (b) (pr ) 2 (c) pr (d)
2
8. If p q r s: :: : , then the proportion not implied is:
(a) q p s r: :: : (b) p r: :: q s: (c) q p r s: :: : (d) s q r p: :: :
9. The ratio of five dozen balls to 16 balls is:
(a) 15 : 4 (b) 5 : 16 (c) 16 : 5 (d) 1 : 3

10. The mean propor tional to 2 and 8 is:
(a) 1 (b) 4 (c) 16 (d) 32

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