Raj alone can complete a work in 20 days and Pratap alone can complete the same work in half of the time taken by Raj. In how many days will both together complete 3/5 part of the total work ?
Answer & explanation
Correct answer: option 2
Efficiency ∝ $\frac{1}{time}$
Raj : Pratap
Time 20 : 10 = 2 : 1
Efficiency 1 : 2
Let the total work be 20
total efficiency = 1 + 2 =3
$\frac{3}{5}$ of the work = 12 units
Time taken to complete this work = $\frac{work}{efficiency}$
= $\frac{12}{3}$ = 4days