The World of Numbers | Exercise 3.3

Question 3

Find the difference:

(i) 5614\frac{5}{6} - \frac{1}{4} (ii) 11834\frac{11}{8} - \frac{3}{4} (iii) 79(23)-\frac{7}{9} - \left(-\frac{2}{3}\right)

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Solution

We will find the difference between the given fractions.

Step 1 — Subtracting 14\frac{1}{4} from 56\frac{5}{6}

First, we find the Least Common Multiple (LCM) of the denominators. The denominators are 6 and 4. The LCM of 6 and 4 is 12. Now, we convert both fractions to have a common denominator of 12.

56=5×26×2=1012\frac{5}{6} = \frac{5 \times 2}{6 \times 2} = \frac{10}{12}

14=1×34×3=312\frac{1}{4} = \frac{1 \times 3}{4 \times 3} = \frac{3}{12}

Next, we subtract the second fraction from the first.

1012312\frac{10}{12} - \frac{3}{12}

=10312= \frac{10 - 3}{12}

712\boxed{\frac{7}{12}}

Diagram 1

Step 2 — Subtracting 34\frac{3}{4} from 118\frac{11}{8}

We find the LCM of the denominators. The denominators are 8 and 4. The LCM of 8 and 4 is 8. We convert the second fraction to have a common denominator of 8.

34=3×24×2=68\frac{3}{4} = \frac{3 \times 2}{4 \times 2} = \frac{6}{8}

Now, we subtract this from the first fraction.

11868\frac{11}{8} - \frac{6}{8}

=1168= \frac{11 - 6}{8}

58\boxed{\frac{5}{8}}

Diagram 2

Step 3 — Subtracting 23-\frac{2}{3} from 79-\frac{7}{9}

First, we simplify the expression. Subtracting a negative number is the same as adding a positive number.

79(23)=79+23-\frac{7}{9} - \left(-\frac{2}{3}\right) = -\frac{7}{9} + \frac{2}{3}

Next, we find the LCM of the denominators. The denominators are 9 and 3. The LCM of 9 and 3 is 9. We convert the second fraction to have a common denominator of 9.

23=2×33×3=69\frac{2}{3} = \frac{2 \times 3}{3 \times 3} = \frac{6}{9}

Now, we add the fractions.

79+69-\frac{7}{9} + \frac{6}{9}

=7+69= \frac{-7 + 6}{9}

19\boxed{-\frac{1}{9}}

Diagram 3

Answer

(i) 712\frac{7}{12} (ii) 58\frac{5}{8} (iii) 19-\frac{1}{9}

More questions in Exercise 3.3

Q1

Prove that the following rational numbers are equal:

(i) 23\frac{2}{3} and 46\frac{4}{6} (ii) 54\frac{5}{4} and 108\frac{10}{8} (iii) 35-\frac{3}{5} and 610-\frac{6}{10} (iv) 93\frac{9}{3} and 33

Q2

Find the sum:

(i) 25+310\frac{2}{5} + \frac{3}{10} (ii) 712+58\frac{7}{12} + \frac{5}{8} (iii) 47+314-\frac{4}{7} + \frac{3}{14}

Q3

Find the difference:

(i) 5614\frac{5}{6} - \frac{1}{4} (ii) 11834\frac{11}{8} - \frac{3}{4} (iii) 79(23)-\frac{7}{9} - \left(-\frac{2}{3}\right)

Q4

Find the product:

(i) 23×310\frac{2}{3} \times \frac{3}{10} (ii) 711×58\frac{7}{11} \times \frac{5}{8} (iii) 47×514-\frac{4}{7} \times \frac{5}{14}

Q5

Find the quotient:

(i) 23÷310\frac{2}{3} \div \frac{3}{10} (ii) 711÷58\frac{7}{11} \div \frac{5}{8} (iii) 47÷514-\frac{4}{7} \div \frac{5}{14}

Q6

Show that:

(12+34)×83=12×83+34×83\left(\frac{1}{2} + \frac{3}{4}\right) \times \frac{8}{3} = \frac{1}{2} \times \frac{8}{3} + \frac{3}{4} \times \frac{8}{3}

Q7

Simplify the following using the distributive property:

79(6734)\frac{7}{9}\left(\frac{6}{7} - \frac{3}{4}\right)

Q8

Find the rational number xx such that:

56(x+35)=56x+12\frac{5}{6}\left(x + \frac{3}{5}\right) = \frac{5}{6}x + \frac{1}{2}

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