A certain number of answer sheets can be checked in 12 days working 5 hours…
2023
A certain number of answer sheets can be checked in 12 days working 5 hours each day by 9 examiners. For how many hours a day should 4 examiners work to check twice the number of answer sheets in 30 days?
- A.
12
- B.
13
- C.
9
- D.
11
Attempted by 12 students.
Show answer & explanation
Correct answer: C
Key idea: total work is proportional to number of examiners × hours per day × days.
Compute the total initial work in examiner-hours: 9 examiners × 5 hours/day × 12 days = 540 examiner-hours.
For twice the number of answer sheets the required work = 540 × 2 = 1080 examiner-hours.
Let h be the hours per day needed for 4 examiners over 30 days. Then 4 × h × 30 = 1080.
Solve for h: h = 1080 ÷ (4 × 30) = 1080 ÷ 120 = 9.
Answer: 9 hours per day