Correct Answer - Option 4 :
\(7\frac{4}{5}\) days
Given:
Work done by Amit = 15 days
Work done by Balbir = 10 days
Amit alone works = 3 days after Balbir joins him
Formula used:
Work done = Time × Efficiency
Calculation:
LCM of 15 and 10 = 30
Amit 1 day work = 30/15 = 2 units
Balbir 1 day work = 30/10 = 3 units
Amit alone work for 3 days = 2 × 3 = 6 days
Remaining work = (30 – 6) = 24 days
Work done by Both = 24/(2 + 3)
⇒ 24/5 = \(4\frac{4}{5}\) days
Work will be finished by Amit and Balbir = (\(4\frac{4}{5}\) + 3) = \(7\frac{4}{5}\) days
∴ Required time to finished the work is \(7\frac{4}{5}\) days