Maths question from Social Forest Worker exam, 2026 by JKSSB
A, B, and C can complete a complex engineering project in 25 days working together. The ratio of their individual efficiencies is 4:3: 5 respectively. The project begins with all three working together. However, the following events occur: After 5 days, A leaves the project. To compensate for A's departure, B increases his efficiency 33.3%, while C continues to work at his original efficiency. C leaves d days before the completion of project. The entire project is completed in exactly 35 days. What is the value of d?
Last updated Jul 21, 2026
Correct Answer:
Option C —
5
1. Calculate the Total Work Required
The daily efficiencies of A, B, and C are 4, 3, and 5 units per day.
Working together, their combined daily output is 12 units (4 plus 3 plus 5).
Since they can complete the project in 25 days, the total project size is 300 units (12 units per day multiplied by 25 days).
2. Work Completed in the First 5 Days
For the first 5 days, all three work together at their combined rate of 12 units per day.
Work completed in these 5 days is 60 units (5 multiplied by 12).
Remaining work to finish is 240 units (300 minus 60).
Remaining time to finish the project is 30 days (35 total days minus the 5 days already spent).
3. Determine Output for the Remaining 30 Days
A leaves the project.
B increases efficiency by one-third (33.3 percent), raising B's daily output from 3 to 4 units.
C remains at an efficiency of 5 units per day.
B stays for the entire remaining 30 days, completing 120 units of work (30 days multiplied by 4 units per day).
4. Calculate Days Worked by C and the Value of d
The work left for C to complete during these 30 days is 120 units (240 remaining units minus B's 120 units).
Since C contributes 5 units per day, C needs 24 days to complete 120 units (120 divided by 5).
Since the second phase lasts 30 days and C only works for 24 days, C leaves 6 days before the project ends (30 minus 24).
Conclusion
The value of d is 6.
Answer verified by Quintessence Classes faculty — Karan Nagar, Srinagar.
