A can complete a work in 20 days, while B can complete the same work in 25 days. Both worked together for 10 days and then C alone completed the remaining work in 10 days. In how many days will A, B and C together complete the same work?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 10 days.
Entire work = Work done each day × Time taken to finish the entire work
LCM (20, 25) = 100
Let, the total work done by A and B = 100
A does each day = (100 ÷ 20) = 5 units
B does each day = (100 ÷ 25) = 4 units
So, in 10 days A and B together do = (5 + 4) × 10 = 90 units
Remaining work = (100 - 90) = 10 units
So, C does each day = (10 ÷ 10) = 1 unit
Then, A, B and C together do each day = (5 + 4 + 1) = 10 units
Hence, the time taken by them to finish the work together = (100 ÷ 10) = 10 days