# Sarin and his coin bank part 45 (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 presents the Math Concept, the Math Questions with solutions that teaches in Singapore Primary Schools. You or the kids can learn the skills 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, Fraction and Problem Solving.

You can read the posting on Sarin and his coin bank for the story of coin bank.

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

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

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

Upper primary school mathematics question UPQ450

Hairu and Sarin shared \$425 in the coin bank. After Hairu spent 2/3 of his money and Sarin spent ¼ of his money, Sarin’s money was twice as much as Hairu’s money. Find the amount of money Sarin had in the end.

Solution:

Start the math model with Sarin’s money was twice as much as Hairu’s money at the end and then adding in their fraction of money spent to get the math model. From the model

17units = 425

1 unit = 25

The amount of money Sarin had at the end = 6 × 25 = \$150

Alternative Solution:

Using ratio method

Sarin spent ¼ of his money

In ratio,

S(left) : S(Spent) : S(Total) = 3 : 1 : 4

Hairu spent 2/3 of his money

In ratio,

H(left) : H(Spent) : H(Total) = 1 : 2 : 3

The amount that Sarin finally left is twice as much as Hairu

The two ratios become

S(left) : S(Spent) : S(Total) = 3 : 1 : 4 = 6 : 2 : 8

H(left) : H(Spent) : H(Total) = 1 : 2 : 3 = 3 : 6 : 9

They shared \$425 at first

17 units = 425

1 unit = \$25

The amount Sarin had at the end = 6 × 25 = \$150

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