Mohan, Aman and Sohan together can complete a work in 18 days. If Mohan can work thrice as faster than Aman and Aman can work twice as faster than Sohan, then in how many days Sohan alone can complete the same work?

Mohan, Aman, and Sohan together can complete the work in 18 days.

Work efficiency:

Mohan works thrice as fast as Aman.

Aman works twice as fast as Sohan. 

Total work = Efficiency $$\times$$ Time

Solution: 

Let the Sohan efficiency is 1 unit/days 

Then, Aman efficiency = 2 unit/day

Mohan efficiency = 6 unit/day 

Total work done by Mohan + Aman + Sohan

= $$18 \times (1 + 2 +6) = 18 \times 9 = 162\, unit$$  

Time taken by Sohan to complete the work alone,

= $$\frac{162}{1} = \bf 162 \,days$$ 

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