Correct Answer - Option 2 : 105/13 days
Given:
A is 30% more efficient than B.
C is 20% more efficient than B.
Concept used:
Total Work = Efficiency × Time
Calculation:
Let the efficiency of B be 100.
Efficiency ratio,
A ∶ B = 130 ∶ 100 ---(1)
B ∶ C = 100 ∶ 120 ---(2)
From equation (1) and (2), we get
A ∶ B ∶ C = 130 ∶ 100 ∶ 120
A ∶ B ∶ C = 13 ∶ 10 ∶ 12
Total Work = Efficiency × Time
Total Work = (13 + 10 + 12) × 5 = 35 × 5 = 175
TimeA = [3/4th of the total work]/Efficiency of A
TimeA = {(3/5) × 175}/13
TimeA = 105/13 day
∴ 'A' alone complete 3/5th of the total work in 105/13 days.