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Swastik went to a shop to buy 10 candles. The cost of a pack of 4 candles is `32. How

will we find the cost of the required number of articles when the cost of some articles is
given?

In such situations, first find the cost of one article and then the cost of the required number

of articles.

Here, the cost of 4 candles = `32.
32 4 candles
pack of
So, the cost of 1 candle will be `(32 ÷ 4) = ` = `8.
4
So, the cost of 10 candles will be `(8 × 10) = `80.

Thus, Swastik will pay `80 for 10 candles of the same kind.

Example 3: The cost of 2 dozen bananas is `120. What will be the cost of 6 bananas?

Solution: Cost of 2 dozen bananas = `120

So, the cost of 1 banana = ` 120 = `5 ( 2 dozen = 24 units)
24

Therefore, the cost of 6 bananas will be `(5 × 6) = `30.

Practice time 10a

1. 1 dozen erasers cost `36. Find the cost of:

( a) 3 erasers (b) 6 erasers (c) 9 erasers
2. If 5 kg of rice costs `325, then find the cost of 8 kg of rice.

3. 5 pens cost `20. Find the cost of 8 such pens and then 15 pens.
4. 35 apples cost `245. Find the cost of 15 apples.
5. The cost of 18 books is `2250. Find the cost of 4 books.

6. 12 kg of onions cost `72. Find the cost of
27 kg of onions. Think Tank Critical Thinking
7. The cost of 4 shirts is `600. Find the cost of The cost of 5 pens is the
one dozen shirts. same as the cost of 2
notebooks. If the cost of 3
8. Mr Gupta earns `6,30,000 in 9 months. notebooks is ₹120, what is
How much will he earn in 3 years? the cost of 8 pens?

Knowledge Desk

Long ago, people didn’t use money. They used the barter system for trading goods directly.
A farmer might trade a bag of rice for a pair of shoes from a shoemaker. The problem was,
what if the shoemaker didn’t need rice? Money was invented to solve this problem and make
trading easier for everyone.

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