Solution:
Given:
Time taken by X = 2 × Time taken by Y
Time taken by X = 3 × Time taken by Z
Time to complete work together = 2 days
Concept used:
Efficiency to do a work is inversely proportional to time taken for the same.
Total work = Time × Efficiency
Calculation:
According to the question,
Time ratio, X : Y : Z = 6 : 3 : 2
So, Efficiency ratio = 1/6 : 1/3 : 1/2
Multiply each term by 6
⇒ Efficiency ratio = 6/6 : 6/3 : 6/2 = 1 : 2 : 3
Combined efficiency = 6 units
So, total work = 6 units × 2 = 12 units
Efficiency 'of Y = 2 units
So, time taken by Y alone to do the work = 12/2 = 6 days
∴ Y will finish the work alone in 6 days.