Discuss Forum
1. A and B can do a work in 12 days. B and C can do it is 15 days, and A and C can do it in 20 days. If all of them work together, in how many days they can finish the work?
- A. 25
- B. 25
- C. 25
- D. 25
Answer: Option D
Explanation:
A + B can do the work in 12 days.
In a single day A + B will do 1/12 th portion of the work.
B + C can do the work in 15 days.
In a single day B + C will do 1/15 th portion of the work.
A + C can do the work in 20 days.
In a single day A + C will do 1/20 th portion of the work.
In a day (A + B) + (A + C) + (C + A) will do = (1/12) + (1/15) + (1/20) portion of the work.
2(A + B + C) = (1/12) + (1/15) + (1/20) = 1/5 portion of the work.
Then, (A + B + C) will do = 1/10 portion of the work in a day
A + B + C will complete the work in 10 days.
Post your comments here: