HOTS Mathematics Primary 5 Decimals

A water tank at Amir's HDB flat is completely empty. Tap A fills the tank at 2.4 litres per minute. A drain valve removes water at 0.9 litres per minute. Both Tap A and the drain valve are opened at the same time. How many litres of water are in the tank after 5 minutes?

A 7.5 litres
B 12 litres
C 4.5 litres
D 16.5 litres
Show Worked Solution

Worked Solution

Step 1: Find the net rate of change. Tap A fills at 2.4 L/min; drain removes at 0.9 L/min. Net rate = 2.4 - 0.9 = 1.5 L/min Step 2: Find total water after 5 minutes. Volume = net rate x time = 1.5 x 5 = 7.5 litres Answer: 7.5 litres

Correct answer: 7.5 litres

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