A water tank is being filled by two inlet pipes. Pipe A can fill the tank in 4 hours, while both pipes together can fill the tank in 2 hours. How long does it take to fill the tank using only Pipe B?

2 Hours

this is because one pipe takes 4 hours, and if both pipes take 2 hours, that is cutting the time in half, meaning both pipes pour the same amount and take the same time.

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if i put something wrong your not gonna like it so rather not say nothing.