Raju, Sunil and Vishal can separately finish a work in 20, 30 and 40 days, respectively. In how many days Raju can finish the work, if he is assisted by Sunil and Vishal on alternate days, starting with Sunil?
Answer & explanation
Correct answer: option 1
Efficiency ∝ $\frac{1}{time}$
Raju : Sunil : Vishnu
Time 20 : 30 : 40
Efficiency 6 : 4 : 3
Let the total work be 120
Since Raju is Sunil and Vishnu on alternate days,
The efficiencies will be as follows:
10, 9, 10, 9, 10..................
In 12 days, 114 units of work will be complete
The remaining work i.e. 6 units will be completed by Raju and Sunil together in $\frac{6}{10}$ = $\frac{3}{5}$ days
Total time taken = 12$\frac{3}{5}$ days