Question 77

A can do 1/3rd of a job in 3 days and B can do half of the job in 9 days. If they work on it together, then in how many days can they finish half of the job?

Solution

Let total work to be done = 18 units

A can do 1/3rd of the job in 3 days

=> A's efficiency = $$\frac{1}{3} \times \frac{18}{3}=2$$ units/day

Similarly, B's efficiency = $$\frac{1}{2} \times \frac{18}{9}=1$$ unit/day

=> (A+B)'s 1 day's work = $$2+1=3$$ units/day

$$\therefore$$ Time taken by them to finish half of the job = $$\frac{1}{2} \times \frac{18}{3}=3$$ days

=> Ans - (D)

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