Help in P5 Math Questions
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Can anyone help to show how to use model to solve the following question?
Mary had a total of 413 apples and pears. When 3/8 of the apples were sold, the number of apples left was 237 more than the number of pears. How many pears did Mary have at first?
Thanks in advance?
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My own models :D
Let number of apples by x
Let number of pears be y
x + y = 413 --- 1
5x/8 -237 = y --- 2
Sub 2 into 1
x + 5x/8 -237 = 413
13x/8 = 650
x = 400
Sub x = 400 into 1
400 + y = 413
y = 413 - 400
y = 13
The number of apples is 400 and the number of pears is 13.
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Destiny,
Really appreciate your prompt help. But is it possible to use model diagram to show the solution, instead of algebra? I am not sure if P5 kids are taught about Algebra in school.
Thanks once again.
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Sorry. Thats the best i can do. Cant draw models on comp
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Not sure whether this is orthodox method. I'll say it verbally.
Let the apples have 8 blocks and the pear has 1 unit(any length since you don't know how many pears you have).
Then 8 blocks + 1 unit = 413
So when 3/8 apples sold, thus you are left with 5 blocks of apples.
So 5 blocks - 1 unit = 237
Substitute this into 8 blocks + 1 unit = 413
You will get 13 blocks - 237 = 413
13 blocks = 650
Then 1 block = 50
Haha. It took me quite some time.
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d3sT1ny,
Thanks for your help.
After OW4Destiny's reply, I tried to translate his/her solution to Model Diagram. What I got is similar to yours. I couldn't believe that this is for P5 kids who do not know algebra. :(
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Let the no of pears be p.
p + (p+237)/5 x 8 = 413
p = 13
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Seriously. Even with algebra, it took me quite a while to figure out. Its not as straight forward as a simultaneous equation or something.
Primary school maths is getting harder and harder
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No lah. It's not getting tougher. It just that people may not be familiarised with their methods of solving maths.
You can solve it within 3 minutes with algebra but they are using model diagrams. So after many years of not using model diagrams, you will intend to forget it mah.
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It's still a simultaneous equation.
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Hi
Hope this helps.
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Baiyun, once again you have provided an excellent answer using the model drawing
method to solve the question to which the PSLE students are taught to understand.
Your presentation is also very beautiful too.
Indeed, I strongly recommend Baiyun to be the moderator of Homework Forum for
the Primary school Mathematics Questions as he or she provides the answers
using model drawing method, not using secondary school algebra to which many
forumers use to solve primary school mathematics questions. Primary school
mathematics students are only taught the model drawing and the guess and check
method to solve the questions.
Baiyun, well done ! Keep up the good work.
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I have noticed Baiyun's good work as well
very commendable!
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I just wonder ... for baiyun illustration, can P5 kid see how the solution came about?
Certainly a lot of thinking skill involved ....
I find it very difficult to explain to the kid. -
Originally posted by Only-Way-4-Destiny!:
Seriously. Even with algebra, it took me quite a while to figure out. Its not as straight forward as a simultaneous equation or something.
Primary school maths is getting harder and harder
That's because calculators are allowed (from 2009 PSLE onwards) in 5 short-answer questions and all problem sums.