The World of Numbers | Exercise 3.3

Question 5

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}

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Solution

We will divide fractions by multiplying by the reciprocal of the divisor.

Step 1 — Find the first quotient

Let's find the quotient of 23\frac{2}{3} and 310\frac{3}{10}. We change division to multiplication by the reciprocal. The reciprocal of 310\frac{3}{10} is 103\frac{10}{3}. 23÷310\frac{2}{3} \div \frac{3}{10}

=23×103= \frac{2}{3} \times \frac{10}{3}

=2×103×3= \frac{2 \times 10}{3 \times 3}

=209= \frac{20}{9}

209\boxed{\frac{20}{9}}

Step 2 — Find the second quotient

Now, let's find the quotient of 711\frac{7}{11} and 58\frac{5}{8}. We will multiply 711\frac{7}{11} by the reciprocal of 58\frac{5}{8}. The reciprocal of 58\frac{5}{8} is 85\frac{8}{5}. 711÷58\frac{7}{11} \div \frac{5}{8}

=711×85= \frac{7}{11} \times \frac{8}{5}

=7×811×5= \frac{7 \times 8}{11 \times 5}

=5655= \frac{56}{55}

5655\boxed{\frac{56}{55}}

Step 3 — Find the third quotient

Finally, let's find the quotient of 47-\frac{4}{7} and 514\frac{5}{14}. We multiply 47-\frac{4}{7} by the reciprocal of 514\frac{5}{14}. The reciprocal of 514\frac{5}{14} is 145\frac{14}{5}. 47÷514-\frac{4}{7} \div \frac{5}{14}

=47×145= -\frac{4}{7} \times \frac{14}{5}

=4×147×5= \frac{-4 \times 14}{7 \times 5}

=5635= \frac{-56}{35} We can simplify this fraction. Both 56\textbf{56} and 35\textbf{35} are divisible by 7\textbf{7}. =56÷735÷7= \frac{-56 \div 7}{35 \div 7}

=85= -\frac{8}{5}

85\boxed{-\frac{8}{5}}

Answer

(i) 209\frac{20}{9} (ii) 5655\frac{56}{55} (iii) 85-\frac{8}{5}

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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