The blog postings are about the Singapore Math. The readers can learn from the postings on Solving 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.

Read the posting on **Sarin learns concept of ratio in school** to understand the concept of Ratio.

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

**Upper primary school mathematics question UPQ454**

The ratio of Hairu’s stickers to Sarin’ stickers was 3 : 5. After Hairu lost 21 stickers and Sarin got another 30 stickers, the ratio of Hairu’s stickers to Sarin’s stickers became 1 : 2. Find the number of stickers Sarin had in the end.

Solution:

Start the model with the initial ratio of Hairu’s stickers to Sarin’s stickers is 3 : 5

Sarin got 30 more cards and Hairu lost 21 cards and the ratio of cards became 1 : 2

Draw the model

Per the model

From Hairu has

1 unit = 3U – 21

2 units = 6U – 42

From Sarin has

2 units = 5U + 30

1U = 42 + 30 = 72 stickers

The number of stickers Sarin has at the end = 5 × 72 + 30 = 390

Alternative Solution:

The initial ratio of stickers,

Hairu : Sarin = 3 : 5

Hairu lost 21 stickers and Sarin got 30 stickers

Hairu : Sarin : (3U – 21) : (5U + 30) = 1 : 2

6U – 42 = 5U + 30

1U = 72

The number of stickers Sarin has at the end = 5 × 72 + 30 = 390

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