S.chand publication New Learning Composite mathematics solution of class 8 Chapter 1 Rational numbers Exercise 1C

 Exercise 1C

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Q1 | Ex-1B |Class 8 |Rational Numbers | S.Chand | New Learning | Composite maths | myhelper

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Question 1

(a) $-\frac{3}{4}\times \left(-\frac{8}{9}\right)$

Sol :

$=-\frac{3}{4}\times -\frac{8}{9}=\frac{2}{3}$

(b) $\frac{7}{20}\times \left(-\frac{5}{14}\right)$

Sol :

$=\frac{7}{20}\times -\frac{5}{14}=-\frac{1}{8}$

(c) $\frac{-24}{49}\times \frac{35}{36}$

Sol :

$=-\frac{10}{21}$

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Q2 | Ex-1B |Class 8 |Rational Numbers | S.Chand | New Learning | Composite maths | myhelper

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Question 2

(a) $6 \times \frac{5}{3}$

Sol :

$=6\times \frac{5}{3}$

=10

(b) $-18\times -\frac{41}{9}$

Sol :

$=18\times -\frac{41}{69}$

=82

(c) $\frac{19}{9}\times \frac{-7}{38}$

Sol :

$=\frac{19}{9}\times \frac{-7}{38}=-\frac{7}{18}$

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Q3 | Ex-1B |Class 8 |Rational Numbers | S.Chand | New Learning | Composite maths | myhelper

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Question 3

$\frac{25}{4}\times \left(-\frac{8}{9}\right)\times \left(-\frac{42}{11}\right)\times \left(\frac{22}{-35}\right)$

Sol :

$=\frac{5}{2}\times \frac{-4}{3}\times \frac{6}{1}\times \frac{2}{-7}$

$=\frac{-40}{3}=-13\frac{1}{3}$

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Q4 | Ex-1B |Class 8 |Rational Numbers | S.Chand | New Learning | Composite maths | myhelper

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Question 4

Divide:

(a) $\frac{44}{65}\div \frac{11}{13}$

Sol :

$=\frac{4}{5}$

(b) $-\frac{8}{17}\div \frac{24}{-51}$

Sol :

=1

(c) $-\frac{2}{25}\div \frac{4}{35}$

Sol :

$=\frac{-7}{10}$

(d) $115 \div \frac{-23}{5}$

Sol :

-25

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Q5 | Ex-1B |Class 8 |Rational Numbers | S.Chand | New Learning | Composite maths | myhelper

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Question 5

(a) $-1\frac{11}{14}\div \left(-1\frac{7}{18}\right)$

Sol :

$=-\frac{25}{14}\times \frac{-18}{25}=\frac{-1}{7}\times \frac{-9}{1}$

$=\frac{9}{7}=1\frac{2}{7}$

(b) $6\frac{1}{3} \div \left(-2\frac{5}{6}\right)$

Sol :

$=\frac{19}{3}\times \frac{-6}{17}$

$=-\frac{38}{17}=-2\frac{4}{17}$

(c) $-5\frac{1}{4} \div 7$

Sol :

$=\frac{-21}{4}\times \frac{1}{7}=-\frac{3}{4}$

(d) $1\frac{1}{12}\div 2\frac{5}{17}$

Sol :

$=\frac{13}{12}\div  \frac{39}{17}$

$=\frac{13}{12}\times  \frac{17}{39}$

$=\frac{17}{36}$

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Q6 | Ex-1B |Class 8 |Rational Numbers | S.Chand | New Learning | Composite maths | myhelper

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Question 6

Simplify:

$\left(\frac{4}{9} \div \frac{4}{7}\right) \times 1\frac{2}{7}$

Sol :

$=\frac{4}{9}\times \frac{1}{4}\times \frac{9}{7}$

=1

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Q7 | Ex-1B |Class 8 |Rational Numbers | S.Chand | New Learning | Composite maths | myhelper

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Question 7

$\left[5\frac{1}{2}\times \left(-1\frac{5}{6}\right)\right]\div 2\frac{3}{4}$

Sol :

$=\frac{11}{2}\times \left(-\frac{11}{6}\right)\times \frac{4}{11}$

$=-\frac{11}{3}=-3\frac{2}{3}$

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Q8 | Ex-1B |Class 8 |Rational Numbers | S.Chand | New Learning | Composite maths | myhelper

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Question 8

$\left(\frac{8}{-5}\div 12\right) \times \left(\frac{-5}{6}\div (-2)\right)$

Sol :

$=\frac{-8}{5}\times \frac{1}{12}\times \frac{-5}{6}\times \frac{-1}{2}$

$=\frac{-1}{1}\times \frac{1}{3}\times \frac{-1}{6}\times \frac{-1}{1}$

$=-\frac{1}{18}$