Rakesh can do a certain job in 12 days. Vipin is 60% more efficient than Rakesh. How many days will Vipin alone take to do the same job?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → \(7\frac{1}{2}\)
Efficiency is the work done in a day, so the time taken is inversely proportional to the efficiency: a worker who does more each day needs fewer days for the same job.
Vipin is 60% more efficient, so for every 100 units of work Rakesh does in a day, Vipin does 160
Ratio of efficiencies, Rakesh : Vipin \(=100:160=5:8\), so the ratio of times is \(8:5\)
Vipin’s time \(\displaystyle =12\times\frac{5}{8}=\frac{15}{2}=7\frac{1}{2}\) days