Page 24 - SM inner class 7.cdr

Summary

m We have learnt that for addition and subtraction of fractions; the fractions should be like fractions.
Product of numerators
m We have also learnt how to multiply the fractions i e. .,
Product of denominators
1 1
m ‘‘of’’ can be used to represent multiplication. For example, of 6 = ´ 6 = 2
3 3
m The product of two proper fractions is less than each of the fractions that are multiplied. The product of proper
and improper fraction is less than the improper fraction and greater than the proper fraction. The product of
two improper fractions is greater than each of the fractions.
m We can compare the fractions by making the denominators same.
m A reciprocal of fraction is obtained by inverting the numerator and denominator.
m We have seen how to divide two fractions :
(i) While dividing a whole number with a fraction, we multiply the whole number with the reciprocal of that
fraction.
(ii) While dividing a fraction by a whole number we multiply the fraction with the reciprocal of the whole
number.

Review Exercise
Choose cor rect op tion in ques tions given be low :
1
1. 3 ´ = ……………
8
3 1 25 23
(a) (b) (c) (d)
8 2 8 8
1
2. of 20 = ……………
5
(a) 100 (b) 4 (c) 25 (d) 15
1 1
3. ´ =............
7 3
1 3 1 7
(a) (b) (c) (d)
10 7 21 3
1 1
4. ¸ = ……………
3 7
1 3 7
(a) 21 (b) (c) (d)
21 7 3
5. Solve the fol low ing :
5 18 9 4 7 3 3 7
(a) + (b) - (c) - (d) 5 + +
13 13 19 19 16 8 5 10
Fill in the blanks :
1. In an im proper frac tion, the nu mer a tor is __________ the de nom i na tor.
2. Re cip ro cal of 5/11 is ______.
2
3. of 15 is ____.
3
4. A _________ of a frac tion is ob tained by in vert ing it up side down.
5. Vidya and Pratap went for a pic nic. Their mother gave them a wa ter bag that con tained 5 litres of wa ter.
Vidya con sumed 2/5 of the wa ter. Pratap con sumed the re main ing ______wa ter. ___________________
6. A car runs 16 km us ing 1 litre of petrol. _________ dis tance will it cover us ing 3 ¼ litres of petrol

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Mathematics In Focus - 7