Sarin and his coin bank part 24 (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, Math Questions with solutions that teaches in Singapore Primary Schools. You or the kids can aquire the skills of dealing with Math Model, Problem Sum start from Lower Primary School to Upper Primary School level after read the postings. This posting is an Upper primary school math question on Problem Solving.

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

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

Upper primary school mathematics question UPQ260

Sarin likes to fill up his coin bank. He starts to save 2 coins everyday. Each coin is either 20 or 50 cent. To encourage him to continous saving, when he saves for 7 days, his father will give him a $1 coin. After 182 days, Sarin has total $133.90.
a) How many 50 cent coins did Sarin have?
b) How many coins did he have?

Solution:

            Sarin’s father gives Sarin a $1 coin after every 7 days

            The number of $1 coins collected by Sarin = 182 ÷ 7 = 26

            The amount of money collected by Sarin from his father = 26 × 1 = $26

            The amount he saved in 182 days = 133.90 – 26 = $107.90

            If the saving are all 20cent coins

            The total amount saving = 2 × 182 × 0.20 = $72.80

            The gap = 107.90 – 72.80 = $35.10

            The different = 0.5 – 0.2 = $0.3

            The number of 50cent coins = 35.10 ÷ 0.3 = 117

            The amount of money from 50cent coins = 117 × 0.5 = $58.50

            The amount of money from 20cent coin = 107.90 – 58.50 = $49.40

            The number of 20cent coins he have = 49.4 ÷ 0.2 = 247

            The amount of coins he have = 117 + 247 + 26 = 390                       

More Questions on Problem Sum. Click here….

More Questions used Gap Concept. Click here….

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