Engineering Board Exam Reviewer · Work Problems · hard
A and B can do a piece of work in 60 days, B and C in 35 days, and A and C in 30 days. Working together, how many days can all of them finish the work?
- 19.51
- 25.45
- 30.12
- 35.87
Answer
B. 25.45
Solution
1/A+1/B=1/60; 1/B+1/C=1/35; 1/A+1/C=1/30. Adding all three: 2≤ft(1/A+1/B+1/C )=11/140, so 1/A+1/B+1/C=11/280, giving T=25.45 days.
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