Person A is twice as efficient as Person B. Person B can

Solution

According to the question,

Time taken by ‘A’ to complete the work = 32/2 = 16 days

Time taken by ‘C’ to complete the work = 16 + 4 = 20 days

Let the total work = 160 units

Efficiency of ‘A’ = 160/16 = 10 units/day

Efficiency of ‘B’ = 160/32 = 5 units/day

Efficiency of ‘C’ = 160/20 = 8 units/day

When they work together for 7 days, work done = (10 + 5 + 8) × 7 = 161 units

Therefore, maximum number of days they can work together such that the work doesn’t get completed is 6 days.