A can do a piece of work in 15 days. B is 25% more efficient than A, and C is 40% more efficient than B. A and C work together for 3 days and then C leaves. A and B together will complete the remaining work in :
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 3 days
Concept
Time and efficiency show inverse relation
Application
Let efficiency of A = 4 units
Therefore efficiency of B = 4 x 125/100 = 5 units
Efficience of C = 5 x 140/ 100 = 7 units
Therefore efficiency ratio of A, B and C = 4 : 5 : 7
A completes the work in 15 days, it means total work done by A = 15 x 4 = 60 units
Work done by A & C together in 3 days = 3 x ( 4 + 7) = 33 units
work left = 60 - 33 = 27 units
Now c leaves
Remaining Work done by A & B together will be completed in = 27 / ( 4 + 5) = 27 / 9 = 3 days