Pipe A can fill a tank of capacity 350 litres in $$3\frac{1}{2}$$ minutes. Pipe B can fill a tank of capacity 780litres in $$8\frac{2}{3}$$ minutes. How long (in min)will it take to fill a tank of capacity 1615 litres, if both pipes are opened together?
Efficiency = capacity/time
Time taken by pipe A =Â $$3\frac{1}{2} = \frac{7}{2}$$
Efficiency of pipe A = 350$$ \times \frac{2}{7}$$ = 100
Time taken by pipe B =Â $$8\frac{2}{3} =Â \frac{26}{3}$$
Efficiency of pipe B = 780Â $$ \times \frac{3}{26}$$ = 90
Efficiency of pipe A and B = 100 + 90 = 190Â
time taken by both pipes to fill the 1615 liters = 1615/190 = $$8\frac{1}{2}$$
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