Correct Answer - Option 2 : 1:2:3
Concept: Time is inversely proportional to efficiency.
Solution:
Let efficiencies of A, B, C be 6, 3, 2 units respectively.
So, ratio of efficiencies = 6 : 3 : 2
Ratio of time taken =\(1 \over 6\): \(1 \over 3\) : \(1 \over 2\)
= 1 : 2 : 3