Page 211 - Ganit Kaushal

2 3
Ex 5. Geeta bought metre of lace and Shamim bought metre of the same lace to put a complete border
5 4
on a tablecloth whose perimeter is 1 metre long. Find the total length of the lace they both have bought.
Will the lace be sufficient to cover the whole border? (NCERT)
4 35
2 3 2 ×+ × 815 23 3
+
Sol. The total length of the lace = + = = = = 1 metres
×
5 4 54 20 20 20
Yes, the lace will be sufficient to cover the whole border because it is more than one metre.
Ex 6. Complete the adjoining addition-subtraction box.
2 4 6 1 2 3 2 4
Sol. We have, + = = 2, + = = 1, 3 3
3 3 3 3 3 3 1 2
−
1 4
−
2 −= 21 = , − 2 = 42 = 2 , 3 3
1
3 3 3 3 3 3 3 3
1 2 12 3
+
and + = = = 1
3 3 3 3
Therefore, the given box can be completed as shown here: 2 4
3 3 2
1 2 1
3 3
1 2
3 3 1
1 3 1
Ex 7. On a given day, a labourer earned `358 . Out of this money, he spent `102 on food and ` 46
2 4 5
on other needs. How much money was left with him?
1 3 1 717 411 231
Sol. Money left with the labourer = 358 − 102 − 46 = − −
2 4 5 2 4 5

×
717 ×10 411 ×− 231 4
−
5
= ( LCM (2, 4, 5) = 20)
20
7170 − 2055 924 4191 11
−
= = ` = ` 209
20 20 20
Exercise 7.4
1. Evaluate:

4 15 17 2 1 5 3 1
(a) + (b) + 3 (c) 9 − (d) 6 + 3
17 17 2 6 4 4 5 3
1 1
(e) 9 − 5
2 6 3 1 1

2. Write the correct value in the box: (a) −= 4 , (b) 2 + = 2
8
3. Find the value of:
3 4 2 5 7 11 2 1 1 2 7
(a) 2 + + 1 (b) − + (c) 4 +− 4 (d) 2 −+
5 5 5 12 12 12 3 3 3 3 3
4. Find the value of:
2 1 1 5 5 1 7 1 7 1
61
(a) 4 − 3 + 2 (b) ++ (c) −+ 5 (d) 7 + + 5
3 4 6 9 7 7 3 6 4 6

Fractions 209