Examples of Math Problems: Pump a can fill a tank in 12 minutes. Pump b can fill a tank in 20 minutes. How long to fill a tank with pump a and b together?

Friday, January 17, 2014

Pump a can fill a tank in 12 minutes. Pump b can fill a tank in 20 minutes. How long to fill a tank with pump a and b together?

Rates add linearly, so together they are...

1%2FT=1%2Fa%2B1%2Fb%0D%0A

%0D%0A1%2FT=1%2F12%2B1%2F20=2%2F15%0D%0A

%0D%0AT=15%2F2%0D%0A

so 7 minutes, 30 seconds

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