Question

Ravish takes $2\frac{1}{5}$ minutes to walk across the school ground. Rahul takes $\frac{7}{4}$ minutes to do the same. Who takes less time and by what fraction?

Answer 1

Time taken by Ravish = $2\frac{1}{5}=\frac{(5\times 2)+1}{5}=\frac{11}{5}$ minutes
Time taken by Rahul = $\frac{7}{4}\mathrm{minutes}$
Comparing $\frac{11}{5}\&\frac{7}{4}$, we get:
$$\begin{gathered} \frac{11\times 4}{5\times 4},\frac{7\times 5}{4\times 5}(\mathrm{LCM}\mathrm{of}4\&5\mathrm{is}20,\mathrm{so}\mathrm{will}\mathrm{we}\mathrm{convert}\mathrm{each}\mathrm{fraction}\mathrm{into}\mathrm{an}\mathrm{equivalent}\mathrm{fraction}\mathrm{with}\mathrm{denominator}20.) \\ \frac{44}{20}>\frac{35}{20} \end{gathered}$$

Rahul takes less time, i.e., $\frac{44}{20}-\frac{35}{20}=\frac{44-35}{20}=\frac{9}{20}$ minutes.