Answer-Pipe ‘A’ and pipe ‘B’, together can fill 20% of a tank in 6 hours while pipe...

Time taken by pipe lsquoArsquo and pipe lsquoBrsquo, together to fill the tank 60.20 30 hours Let the total capacity of tank 210 units Efficiency of pipe A B 21030 7 unitshour Efficiency of pipe lsquoCrsquo 21035 6 unitshour Tank filled by pipe A B in 28 hours 28 times 7 196 units Time taken by all three pipes to fill the remaining tank 210 ndash 1967 ndash 6 14 hrs Total time taken 28 14 42 hours

Question

Pipe ‘A’ and pipe ‘B’,

together can fill 20% of a tank in 6 hours while pipe ‘C’ takes 35 hours to empty it. Pipe ‘A’ and pipe ‘B’ were opened together. After 28 hours, pipe ‘C’ is also opened. Find the total time taken to fill the empty tank this way.

A 30 hours

B 42 hours

C 40 hours

D 49 hours

E 35 hours