Question 96

Two pipes A and B canfill an empty tank independently in 20 minutes and 30 minutes respectively. To fill the empty tank both of the pipes were opened at a time and after 4 minutes tap A is closed. The total time (in minutes) takes to fill the tank is

Solution

Let the capacity of tank = 60litres

Speek of A = 60/20 = 3litres/min

Speed of B = 60/30 = 2 litres/min

In 4 min, A will fill 12l and B will fill 8 l. Total 20 litres

Left = 40 litres

Time required by B to fill remaining = 40/2 = 20 min

Total time = 24min

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