Question

tap A can fill tank in 20min and tap B in 15min. Both taps are opened and after 3min tapB is closed. how long will it take to fill the tank

Answer 1

Part of the tank filled by both taps in 5 min

=5×(120+160)=5×(6+2)120=824=135×(120+160)=5×(6+2)120=824=13 

Therefore, Remaining part = (1−13)=23(1−13)=23

Therefore, 160160 part is now filled in 1 min.

Therefore, 2323 part is now filled in 60×2360×23 = 40 mm