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Question
primary 6 | Maths
| Ratio
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Nanyang SA1
Ruby and Steve : Max = 2 : 3
Total = 2 units + 3 units = 5 units
Since each child had the same number of sweets in the end, the number of units they get should be the same.
But 5 units cannot be divided by 3. We should multiply by 3 to make it divisible by 3.
5 units x 3 = 15 units
Each child has 5 units in the end.
Since we multiplied the 5 units by 3, the above ratio also has to be multiplied by 3.
So at first, Ruby and Steve : Max = 2 : 3
= 6 : 9
As each child has 5 units in the end, Ruby and Steve now have 10 units combined.
Now, Ruby and Steve : Max = 10 : 5
So that's a increase of 4 units from the total Ruby and Steve had at first.
Total that Max gave to the two of them
= 9 sweets + 23 sweets = 32 sweets
32 sweets = 4 units
1 unit = 32 sweets ÷ 4 = 8 sweets
Sweets Ruby had in the end = 5 units
= 5 x 8 sweets
= 40 sweets
Sweets Steve had at first
= 5 units - 23 sweets that Max gave him
= 40 sweets - 23 sweets
= 17 sweets
See 1 Answer
As a result of this misconception it is not known how much Ruby and Steve have in the end, since only their total is known. So how much Steve had at first cannot be determined as well.
(In your working, Ruby has 192 sweets in the end but Ruby + Steve has 160 in the end. So that's not possible since she cannot have more than their combined total)