In how many minutes?

You have accidentally left out the plug and are attempting to fill the bath with both 2 taps full on. The hot tap takes 6 minutes to fill the bath, the cold tap takes 4 minutes, and the water empties through the plug hole in 12 minutes. In how many minutes will the bath be filled?

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3 minutes. This is solved by 1/6 + 1/4 – 1/12 = 0.166 + 0.25 – 0.083 = 0.333 1/0.333 = 3 minutes

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