# Sarin learns rate of change in school Part 1 (Math Question)

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The blog postings are about the Singapore Math. The readers can learn from the postings on Solving Singapore Primary School Mathematics. You or your kids can learn dealing with Math modeling, Problem Sum from Lower Primary School to Upper Primary School level in Singapore school. This posting is a primary school math question on Fraction, Volume and Flow Rate.

Read the posting on Sarin learns rate of change in school (Math Concept) to learn about concept of speed and relative speed.

You can read the posting on Sarin learns Perimeter, Area and Volume in school(Math Concept) to learn the concept of volume.

To read also the posting on Sarin learns the concept of Fraction (mathematics concept) to understand the concept of Fraction.

Upper primary school mathematics question UPQ193

Sarin is filling up a tank of water from a tap. The water flows from the tap at a rate of 4 l per minute into a tank measuring 60 cm by 20 cm by 30 cm. How long will it take to fill up 2/3 of the tank?

Solution:

The total volume of the tank = 60 × 20 × 30 = 36000 cm3 = 36 l

To fill 2/3 of the tank

Draw the volume model

From the above model

3 units = 36

1 unit = 12 l

The volume of water to fill = 12 × 2 = 24 l

The flow rate of water is 4 l per minute

The time require to fill 2/3 of the tank = 24 ÷ 4 = 6 min