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You can click here and read the posting A family in Singapore about Sarin’s family.
Challenge yourself with the question before look for the given solution‼!
Upper primary school mathematics question UPQ532
Every household in Singapore need to pay utilities bill to the utility service provider monthly. The service provider In Singapore, the water and electrical service is provided by Singapore power. They record the number of units of water and electrical each household comsumed and sent out the statements to each household to make payment.
Sarin family recieve the monthly bill statement every end of the month and his father makes payment via the service counter.
The table below shows the rates of charges for water consumption in a month.
Sarin’s family used 44 units of water per the bill. His father paid the cashier a 50 dollar note and some 50-cent and 20-cent coins. The number of 50-cent coins is half of 20-cent coins. How many 20-cent coins did the cashier receive from his father?
The amount of water comsumed by Sarin family ==> 44 units = 30 + 14
The cost for 1st 30 units consumed è 1.37 × 30 = $41.10
The cost of subsequent 14 units consumed ==> 1.6 × 14 = $22.40
The total cost ==> 41.10 + 22.40 = $63.50
The cashier received a 50 dollar note,
63.50 – 50 = $13.50 is paid in term of coins
The number of 50-cent coins is half of 20-cent coins,
The value of a set of coins è 0.5 + 0.2 + 0.2 = $0.9
The number of set of coins ==> 13.5 ÷ 0.9 = 15
The number of 20-cent coins = 2 × 15 = 30