Correct Answer - Option 1 : 8 days
Given:
Raju can complete a work in 20 days
Shyam can complete a work in 30 days
Calculations:
According to the question, we have
Total work = LCM of 20 and 30 = 60
Efficiency of Raju = 60 ÷ 20 = 3 unit per day
Efficiency of Shyam = 62 ÷ 30 = 2 units per day
Work done by Shyam in 10 days is
⇒ Work done by Shyam in 10 days = 10 × 2
⇒ Work done by Shyam in 10 days = 20 units
Remaining work done by Raju and Shyam together is
⇒ Remaining work = 60 - 20
⇒ Remaining work = 40 units
So, 40 units work was done by Raju and Shyam together
⇒ Number of days = 40/(3 + 2)
⇒ Number of days = 8 days
∴ Raju worked from the beginning for 8 days.