Question

Margaret’s bottle of shampoo is 7/8 full. She uses 1/3 of the shampoo in the bottle to wash the dog. Estimate what fraction of shampoo is left. Use whole numbers and benchmark fractions to explain.

Answer 1

Fraction of shampoo left = $\frac{13}{24}$

Solution:

Given fraction of full shampoo  $=\frac{7}{8}$.

Fraction of shampoo Margaret used  $=\frac{1}{3}$

Fraction of shampoo left = Full shampoo – fraction of shampoo used

                                          $=\frac{7}{8}-\frac{1}{3}$

To make the denominators same do cross multiplication.

                                          $=\frac{7\times3}{8\times3}-\frac{1\times8}{3\times8}$

                                          $=\frac{21}{24}-\frac{8}{24}$

                                          $=\frac{21-8}{24}$

                                          $=\frac{13}{24}$

Hence $\frac{13}{24}$ of the shampoo bottle is left.