Q12
Ankita is twice as efficient as Bipin, while Bipin is twice as efficient as Chandan. All three of them start together on a job, and Bipin leaves the job after 20 days. If the job got completed in 60 days, the number of days needed by Chandan to complete the job alone, is
Answer: 340
Key idea: Assign efficiencies in units of work per day.
Let Chandan do 1 unit/day. Then Bipin does 2 and Ankita does 4.
- Ankita works all 60 days: \(4 \times 60 = 240\) units.
- Chandan works all 60 days: \(1 \times 60 = 60\) units.
- Bipin works 20 days: \(2 \times 20 = 40\) units.
Total work \(= 240 + 60 + 40 = 340\) units. Chandan alone needs \(340 \div 1 = 340\) days.
Hence, the answer is 340.