# Problems on Unitary Method using Direct Variation

We will learn how to solve problems on unitary method using direct variation.

We know, if two quantities are related in such a way that the increase in one quantity results in a corresponding increases in the other and vice versa, then such a variation is called a direct variation.

Solved problems on unitary method using direct variation:

1. A lobour get $980 for 14 days work. How many days should he work to get$2100?

Solution:

This is also a situation of direct variation as money is received for working more days.

$980 is earned by a labour in 14 days.$1 is earned by a labour in 14/980 days.

$2100 is earned by a labour in 14/980 × 2100 days. Therefore,$2100 is earned by a labour in 30 days.

2. If 4 men and 5 women can earn $480 in a day, find how much 9 men and 11 women will earn in a day? Solution: This is a situation of direction variation. More men can earn more in a day. In a day 4 men can earn$ 480

1 men can earn $480/4 and 9 men can earn$480/4 × 9 = $1080 Also, 5 women can earn$ 480 and 1 woman can earn $480/5 =$96

11 women can earn = $96 × 11 =$1056

Therefore, 9 men and 11 women can earn $(1080 + 1056) =$ 2136

3. A car travels 360 km in 60 liters of petrol. How much distance will it cover in 12 liters of petrol?

Solution:

This is also a situation of direct variation.

Less quantity of petrol, less distance covered.

In 60 liters of petrol, distance covered = 360 km.

In 1 liter of petrol, distance covered = 360/60 km.

In 12 liters of petrol, distance covered = 360/60 × 12 km

Therefore, in 12 liters of petrol, distance covered = 72 km.

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Inverse Variation Using Method of Proportion

Problems on Unitary Method using Direct Variation

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