AC Lim's answer to Reanne Ng's Primary 5 Maths Fractions Singapore question.
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Hope this help
Date Posted:
5 years ago
Why is it 28u-27u? Where did the 28u come from?
28u is the total money he mother gave.
7 days —-> 3/4 = 21/28
So 7 days = 21u
1 day = 3u
By end of 9 days=9x3u =27u
Left 28u-27u =$10
7 days —-> 3/4 = 21/28
So 7 days = 21u
1 day = 3u
By end of 9 days=9x3u =27u
Left 28u-27u =$10
Rennie, the term ‘units’ in itself is arbitrary. In other words, we can allocate units to whichever quantity we wish to calculate. Regardless of how ‘units’ is defined in the question, the final answer should be the same.
In the tutor’s workings, the tutor used 28 units for easy computation later since 7 x 4 = 28 (the base of the fraction is 4, so to make calculations easier, we get rid of the base by multiplying the denominator).
3/4 of the money being used is represented in the units form by 21 units out of 28 units used within 7 days. So the starting is 28 units Long.
Then in one day, 3 units are being used.
At this rate, we see that 27 units will be used by the 28th day, leaving 1 unit left which equals $10.
The original sum of money is 28 units, or $280.
In the tutor’s workings, the tutor used 28 units for easy computation later since 7 x 4 = 28 (the base of the fraction is 4, so to make calculations easier, we get rid of the base by multiplying the denominator).
3/4 of the money being used is represented in the units form by 21 units out of 28 units used within 7 days. So the starting is 28 units Long.
Then in one day, 3 units are being used.
At this rate, we see that 27 units will be used by the 28th day, leaving 1 unit left which equals $10.
The original sum of money is 28 units, or $280.
I had the same question thank you so much for helping I had the same question
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