ACS Primary 2009 PSLE Math Prelim Paper 2 Q12

Water flows from Tap A at a rate of 250 ml per minute and from Tap B at a rate of 350 ml per minute. When both taps are turned on for 9 minutes, the water from both taps fill a container with a square base of side 25 cm. What is the height of the water level?

Solution

Tap A
1 min --> 250 ml
9 min --> 9 x 250 ml = 2250 ml

Tap B
1 min --> 350 ml
9 min --> 9 x 350 ml - 3150 ml

Total --> 2250 ml + 3150 ml = 5400 ml


Volume of cuboid = Base area x height
5400 cubic cm = 25 cm x 25 cm x height
5400 cubic cm = 625 square cm x height
height = 5400 cubic cm divided by 625 square cm
height = 8.64 cm

Answer: 8.64 cm

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