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1
Example 2: Narayan goes for a morning walk every day. If he spends of an hour each
day on it, how many hours will he spend in a week? 3
1
Solution: Narayan spends of an hour on his morning walk every day.
3
1
7
1
Therefore, in a week he will spend 7 × = 7 × 1 = = 2 hours.
3 3 3 3
1
Thus, Narayan will spend 2 hours on his morning walk in a week.
3
3
Example 3: Siya purchased 5 kg of mangoes for `32 per kg. How much did she pay for
4
them?
Solution: Cost of 1 kg of mangoes = `32
3 23
Weight of mangoes purchased = 5 kg = kg
4 4
3
Amount paid by Siya for 5 kg of mangoes
4

= ` 32 × 23 = ` 32 × 23 = `(8 × 23) = `184
4 4
3
Thus, Siya paid `184 for 5 kg of mangoes.
4

Multiplication of a Fraction by another Fraction

To multiply two or more fractions, multiply their numerators and denominators separately,
to get the numerator and the denominator of the product, respectively.

Product of two fractions = Product of numerators
Product of denominators
Example 4: Multiply the following.

3
3
4
2
( a) × (b) × × 6
5 7 4 9 20
Solution: 1 1 2
4
3
2
3
( a) × = 3 × 2 = 6 (b) × × 6 = 3 × 4 × 6 = 1 × 1 × 2 = 2 = 1
5 7 5 × 7 35 4 9 20 4 × 9 3 1 × 20 1 × 1 × 20 20 10
1
3
Example 5: A painter uses L of paint to colour 1 m of the FACTS
5 Š The product of two proper
wall. How much paint does he need to colour 2 1 m of the wall? fractions is always less
4 than the given fractions.
3
3
Solution: We have: × 2 1 = × 2 × 4 + 1 Š The product of two improper
5 4 5 4 fractions is always greater
than or equal to the given
9
= 3 × = 3 × 9 = 27 = 1 7 L fractions.
5 4 5 × 4 20 20
Thus, the painter needs 1 7 L of paint to colour 2 1 m of the wall.
20 4

92 Mathematics-5