The blog postings are about the Singapore Math. The readers can learn from the postings about Solving the Singapore Primary School Mathematics. The blog presents the Math Concept, the Math Questions with solutions that teaches in Singapore Primary Schools. You or the kids will learn the skills of dealing with the Math Problem Solving, the Math Modeling 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.

You can read the posting on **Sarin learns the concept of Ratio (mathematics concept)** to understand the concept of Ratio.

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

**Upper primary school mathematics question UPQ519**

Hairu has 140 fewer stickers than Sarin. If Hairu gives 30 stickers to Sarin, the ratio of the number of stickers he has to the number of stickers Sarin has will be 3 : 7. How many stickers do they have altogether?

Solution:

The final ratio of their ratio is 3 : 7, if Hairu gives Sarin 30 stickers

The math model

Per the model

4 units = 30 + 140 + 30 = 200

1 unit = 50

The number of stickers they have altogether = 10 × 50 = 500

Alternative Solution:

Initially, Hairu has 140 stickers less than Sarin

Their ratio,

Hairu : Sarin = 1U : (1U + 140)

After Hairu gives Sarin 30 stickers,

Their sticker ratio can express as,

Hairu : Sarin = (1U – 30) : (1U + 140 + 30) = (1U – 30) : (1U + 170)

Given final stickers ratio, Hairu : Sarin = 3 : 7

3 parts = 1U – 30 ==> 21 parts = 7U – 210

7 parts = 1U + 170 ==> 21 parts = 3U + 510

7U – 210 = 3U + 510

4U = 720

1U = 180

The number of stickers they have altogether = 180 + 180 + 140 = 500

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