A man completes $\frac{5}{8}$ of a job in 10 days. At this rate, how many more days will it take him to finish the job?
(a)5
(b)6
(c)7
(d)$7 \frac{1}{2}$
Answer
Answer (as printed): B
Explanation
Work done $=\frac{5}{8}$. Balance work $=\left(1-\frac{5}{8}\right)=\frac{3}{8}$. Less work, Less days (Direct Proportion) Let the required number of days be $x$. Then, $$\frac{5}{8}: \frac{3}{8}:: 10: x \Leftrightarrow \frac{5}{8} \times x=\frac{3}{8} \times 10 \Leftrightarrow x=\left(\frac{3}{8} \times 10 \times \frac{8}{5}\right)=6 .$$
Explanation as extracted from the printed page; notation may be imperfect.