Ex.2.7 Q1 fractions-and-decimals Solutions-Ncert Maths Class 7

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Question

Find

i) \(0.4 ÷ 2\)

ii) \(0.35 ÷ 5 \)

iii) \(2.48 ÷ 4 \)

iv) \(65.4 ÷ 6\)

v) \(651.2 ÷ 4 \)

vi) \(14.49 ÷ 7 \)

vii) \(3.96 ÷ 4\)

viii) \(0.80 ÷ 5\)

Text Solution

What is known?

One decimal number and one whole number.

What is unknown?

Quotient of following division.

Reasoning:

Covert decimal into fraction then divide it. To divide fractions, multiply the dividend with reciprocal of divisor.

Steps:

i) \(0.4 ÷ 2\)

\[\begin{align}&=\frac{4}{{10}} \times \frac{1}{2}\left( {0.4 = \frac{4}{{10}}} \right) \hfill \\
&= \frac{2}{{10}} \hfill \\&= \frac{1}{5} \hfill \\&= 0.2 \hfill \\\end{align} \]

ii) \(0.35 ÷ 5 \)

\[\begin{align}&= 0.35 \times \frac{1}{5} \hfill \\&= \frac{{35}}{{100}} \times \frac{1}{5}\quad \left( {0.35 = \frac{{35}}{{100}}} \right) \hfill \\&= \frac{7}{{100}} \hfill \\&= 0.07 \hfill \\\end{align} \]

iii) \(2.48 ÷ 4 \)

\[\begin{align}&= 2.48 \times \frac{1}{4} \\&= \frac{{248}}{{100}} \times \frac{1}{4}\quad \left( {\because 2.48 = \frac{{248}}{{100}}} \right) \\&= \frac{{62}}{{100}} \\&= 0.62\end{align}\]

iv) \(65.4 ÷ 6\)

\[\begin{align}&= 65.4 \times \frac{1}{6} \\&= \frac{{654}}{{10}} \times \frac{1}{6}\quad \left( {\because 65.4 = \frac{{654}}{{10}}} \right) \\&= \frac{{109}}{{10}} \\&= 10.9\end{align}\]

v) \(651.2 ÷ 4 \)

\[\begin{align}&= 651.2 \times \frac{1}{4} \\&= \frac{{6512}}{{10}} \times \frac{1}{4}\quad \left( {\because 651.2 = \frac{{6512}}{{10}}} \right) \\&= \frac{{1628}}{{10}} \\&= 162.8\end{align}\]

vi) \(14.49 ÷ 7 \)

\[\begin{align}&= 14.49 \times \frac{1}{7} \\&= \frac{{1449}}{{100}} \times \frac{1}{7}\left( {\because 14.49 = \frac{{1449}}{{100}}} \right) \\&= \frac{{1449}}{{700}}\\&= \frac{{207}}{{100}}\\&= 2.07\end{align}\]

vii) \(3.96 ÷ 4\)

\[\begin{align}&= 3.96 \times \frac{1}{4} \\&= \frac{{396}}{{100}} \times \frac{1}{4}\quad \left( {\because 3.96 = \frac{{396}}{{100}}} \right) \\&= \frac{{396}}{{400}} \\&= \frac{{99}}{{100}} \\&= 0.99\end{align}\]

viii) \(0.80 ÷ 5\)

\[\begin{align}&= 0.80 \times \frac{1}{5} \\&= \frac{{80}}{{100}} \times \frac{1}{5}\left( {\because 0.80 = \frac{{80}}{{100}}} \right) \\&= \frac{{16}}{{100}} \\&= 0.16\end{align}\]

  
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