# A family in Singapore part 53 (Math Question)

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The blog postings are about the Singapore Math. The readers can learn from the postings about Solving Singapore Primary School Mathematics. The blog presenting the Math Concept, the Math Questions with solutions that teaches in Singapore Primary Schools. You or the kids will able to acquire knowledge of dealing with the Math Modeling, the Math Problem Solving and the Problem Sum from Lower Primary School to Upper Primary School level after reading the blog postings. This posting is an upper primary school math question on Ratio and Problem Sum.

Read also the posting on Sarin learns the concept of Ratio in School (mathematics concept) to understand the concept of Ratio.

Challenge yourself with the question before look for the given solution‼!

Upper primary school mathematics question UPQ480

The ratio of the mass of Sarin to the mass of Fatimah is 5 : 3. The ratio of the mass of Hairu to the mass of Fatimah is 5 : 4. Hairu weighs 30 kg, what is the mass of Sarin?

Solution:

Draw the math model,

The ratio of Hairu’s mass to Fatimah’s mass is 5 : 4

5 units = 30

1 unit = 6 kg

The mass of Fatimah = 4 × 6 = 24 kg

The ratio of Sarin’s mass to Fatimah’s mass is 5 : 3

3 units = 24

1 unit = 8 kg

The mass of Sarin = 5 × 8 = 40 kg

Alternative Solution:

The mass ratio,

Sarin : Fatimah = 5 : 3 = 20 : 12

Hairu : Fatimah = 5 : 4 = 15 : 12

Sarin : Fatimah : Hairu = 20 : 12 : 15

The weigh of Hairu is 30kg

15 units = 30

1 unit = 2kg

The mass of Sarin = 20 × 2 = 40 kg