Page 40 - Start Up Mathematics_7

3. Multiply and write the following in their simplest form:
8 33 11 49 1 3 4 3
(a) × (b) × (c) 7 × 2 (d) 3 × 4
11 64 7 55 4 10 5 4
3 4
4. Find the cost of 6 litres of milk if the cost of milk is ` 21 per litre.
4 5
1
1
5. Find the area of a rectangular plot with length 16 m and breadth 10 m.
2 3
2
6. In a class of 36 students, the number of boys is of the total strength. How many girls
3
are there in the class?
1
7. In a basket having 144 oranges, of the total oranges are rotten. How many of them are
6
in good condition?
1 5
8. To stitch a dress, 4 m cloth is required. If the cost of cloth is ` 77 per metre, find the
2 6
cost of the cloth required for the dress.

Division of Fractions
We are well versed with the mathematical operation of division. Division of fractions also has
the same meaning.
5
1
For example, a rod of m is cut into m long pieces. The number of pieces obtained would be
2 2
5
1
1
5 ÷ = 5 × Reciprocal of = × = 5
2
2 2 2 2 2 1
Therefore, the number of such pieces would be 5.
Case I: Division of a whole number by a fraction
1
Let’s evaluate 6 ÷ , i.e., we need to divide 6 wholes into one-thirds.
3
We represent 6 wholes as 6 strips. Now all the strips are divided into one-thirds.

1
3
1
Therefore, 6 ÷ = 6 × Reciprocal of = 6 × = 18.
3 3 1
Case II: Division of a fraction by a whole number

4
Let’s divide by 2.
5
4
4 ÷ 2 = × (Reciprocal of 2) = × = 4 =
2
4
1
5 5 5 2 10 5
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