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primary 5 | Maths | Rate & Ratio
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Jane lee
Jane Lee

primary 5 chevron_right Maths chevron_right Rate & Ratio chevron_right Singapore

Sorry unable to solve. Can help?

Date Posted: 4 years ago
Views: 278
snell
Snell
4 years ago
*qn is a play on words. confusing ...


spent
Bob's all money: 2u
Amos: u
Amos' all money: u+1800


spent
Bob's all money: 2u
Amos: 4u
Amos' all money: 4u+600


u+1800 = 4u+600
u = 400

Amos had $2200 ;
Bob had $800 at first


...
Jane lee
Jane Lee
4 years ago
Thank you so much !
J
J
4 years ago
This question is a variation of the high-difficulty PSLE problem sum about selling ducks and chickens. Many students stumble upon encountering it.


What we need to realise is that Bob spent all his money in both cases. So this amount doesn't change.

Letting Bob's money be 2 units makes calculation easier, as it can be divided by 2 and also multiplied by 2 to find the amount Amos spent in both cases.

2 units ÷ 2 = 1 unit
2 units x 2 = 4 units

Since Amos's total amount of money doesn't change, the difference in amount he spent equals the difference in amount he had left.

Difference = $1800 - $600 = $1200

$1200 more was spent on one case, so $1200 less remained at the end.

Difference also = 4 units - 1 unit = 3 units

So 3 units = $1200
1 unit = $1200 ÷ 3 = $400
Jane lee
Jane Lee
4 years ago
Tks for the explanation.
J
J
4 years ago
Welcome. Here's the question about chickens and ducks. you can try if you're interested


A farmer has some chickens and ducks. If he sells 2 chickens and 3 ducks every day, there will be 50 chickens left when all the ducks have been sold. If he sells 3 chickens and 2 ducks every day, there will be 25 chickens left when all the ducks have been sold.

a) how many ducks are there?

b) how many chickens are there ?
Jane lee
Jane Lee
4 years ago
Let me challenge it. Tks

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Alysha
Alysha's answer
24 answers (A Helpful Person)
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Official answers by J and Snell ( in the comments)
Jane lee
Jane Lee
4 years ago
Good