Question

A is 50% as efficient as B. C does half of the work done by A and B together in same time in same time. If C alone does the work in 20 days, then A, B and C together can do work in: (a) 2 5 days 3 (b) 2 6 days 3 (c) 6 days (d) 7 days (e) None of these

Answer 1

Step-by-step explanation:

C does half work of A & B  

Work done by C in a day is 1/40

C = 1/(A+B) 2

1/40 = 1/(A+B) 2 

2/40 = 1/A+B

1/A+B = 1/20 

So A & B together take 20 days to complete a work 

Now A, B & C together take 

1/A + 1/B +1/C 

= 1/20 + 1/40 

= 3/40 

= 40/3 days 

= 13.33 days