# Sarin and his coin bank part 24 (Math Question)

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

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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