A, B and C can do a piece of work in 30, 20 and 10 days resp. A is assisted by B on one day and by C on the next day, alternatively. How long would the work take to finish?
Answer & explanation
Correct answer: option 1
1st day work by (A + B) = 2 + 3 = 5
2nd day work by (A + C) = 2 + 6 = 8
Two days work = 5 + 8 = 13
⇒ In 2 days total work done = 13 Units
⇒ In 8 days total work done = 52 Units
⇒ On 9th day (A + B) work = 5
Therefore,
⇒ In 9 days total work done = 57 Units
⇒ Last 3 Units work is to be done by (A+ C) with the efficiency of '8',
So, Total Time to finish the work = 9 +\(\frac{3}{8}\) = 9\(\frac{3}{8}\)