question_answer

A and B can do a piece of work in 15 days. B and C can do the same work in 10 days and A and C can do the same work in 12 days. Time taken by A, B and C together to do the job is-

A)  9 days                         

B)  4 days

C)  6 days                         

D)  8 days

Correct Answer: D

Solution :

 Let the total work be 60. So, Efficiency of \[(A+B),\,(B+C)\]and \[(A+C)\] are 4, 6, and 5 respectively. \[\therefore \]    Time taken by A, B and C together to complete the job. \[=\,\frac{60\times 2}{(4+6+5)}=\frac{120}{15}\] = 8 days.