Q&A - PSLE Math

[atutor2001]

pixiedust:

...Will wait for solution...

Simply :

Let the number of GROUPs of \"7 apples\" be U
Let the number of GROUPs of \"9 oranges\" be V

1 group of apple costs $4 so cost of all apples is $4U
1 group of orange costs $11 so cost of all oranges is $11V
So 4V + 11V = 999

Total number of apples is 7U (there are 7 apples in each group)
Total number of oranges is 9V (there are 9 oranges in each group)
So 7U + 9V = 1000

To find U & V we can draw model or use simultaneous.

[small]

Different way to solve the question.


http://farm6.static.flickr.com/5020/5456292860_49335b2630_z.jpg\">

[atutor2001]

small:

Different way to solve the question.


http://farm6.static.flickr.com/5020/5456292860_49335b2630_z.jpg\">

If the question is :

A bag of oranges were shared among some girls. If each girl received 5 oranges, there would be 4 extra oranges. If each girl received 6 oranges, there would be 4 oranges short.

What should I do, using the same method?

[tianzhu]

anneshirleygilbert:

I did it the Guess and Check method and got the answer after 10 guesses!!! Doubt students sitting in PSLE would have the luxury of time to do 10 guesses.

My answer is 343 apples and 657 oranges; but I'm curious and eager to learn your method.

Hi

Hope this helps.

First I’d like to share the thought process for this solution.

A student should be able to recognize that the number of oranges is a multiple of 9 and the number of apples is a multiple of 7.

I started with a group of 100 for ease of calculation as it’s not too difficult to get 72 oranges and 28 apples to form a group of 100 fruits.

Next multiply by 10 to get 1000 fruits.

Work in group of 63 for an increase/decrease of oranges and apples --- for balancing.

Best wishes

http://farm6.static.flickr.com/5052/5456348000_75a99120c9_b.jpg\">

[small]

atutor2001:

If the question is :

A bag of oranges were shared among some girls. If each girl received 5 oranges, there would be 4 extra oranges. If each girl received 6 oranges, there would be 4 oranges short.

What should I do, using the same method?

Hope this helps.

a)

Multiple of 5 + 4 : 19, 24, 29, 34, 39, 44, 49, 54, 59\t.....
Multiple of 6 - 4 : 20, 26, 32, 38, 44, 50, 56, 62...

There were 44 oranges in the bags.\t\t\t\t\t\t\t\t\t\t\t

b) \t If each girl received 5 oranges, there would be 4 extra oranges.\t\t\t\t\t

\t5 Units + 4 = 44
\t5 Units = 40
\t1Unit = 8

\t8 girls were sharing the oranges.

[small]

tianzhu:

Hope this helps.

Best wishes

http://farm6.static.flickr.com/5052/5456348000_75a99120c9_b.jpg\">

Hi Tianzhu,

Like this method, thanks for sharing the idea. :celebrate:

[atutor2001]

small:

atutor2001:

If the question is :

A bag of oranges were shared among some girls. If each girl received 5 oranges, there would be 4 extra oranges. If each girl received 6 oranges, there would be 4 oranges short.

What should I do, using the same method?

Hope this helps.

a)

Multiple of 5 + 4 : 19, 24, 29, 34, 39, 44, 49, 54, 59\t.....
Multiple of 6 - 4 : 20, 26, 32, 38, 44, 50, 56, 62...

There were 44 oranges in the bags.\t\t\t\t\t\t\t\t\t\t\t

b) \t If each girl received 5 oranges, there would be 4 extra oranges.\t\t\t\t\t

\t5 Units + 4 = 44
\t5 Units = 40
\t1Unit = 8

\t8 girls were sharing the oranges.

Hi small

Multiple of 5 + 4 : 9, 14....

Multiple of 6 - 4 : 2, 8, 14, ....

Actually the first common number is 14, why is 14 not the number of oranges? Thanks

[small]

Hi atutor2001,


You are right too, I overlooked this, still have long long way to learn it. :oops:


I think normally the setter will specify the range of oranges for the question. If not, both 14 and 41 are considered correct..

[stary]

small:

tianzhu:

Hope this helps.

Best wishes

http://farm6.static.flickr.com/5052/5456348000_75a99120c9_b.jpg\">

Hi Tianzhu,

Like this method, thanks for sharing the idea. :celebrate:

Me too, otherwise I always use guess n check which are sometimes rather tedious. Simultaneous equation only taught in Secondary, wonder can it be used in Primary.
Stary

[small]

stary:

Me too, otherwise I always use guess n check which are sometimes rather tedious. Simultaneous equation only taught in Secondary, wonder can it be used in Primary.

Stary

Hi Stary,

Should not be a problem as there are so many ways to solve the Maths questions and it very depends on the kids' understanding to apply the suitable method to it.
[quote]Not all methods are suitable for the children. Some methods work very well for the child, while others may not be suitable. However, the child can easily learn any technique you prescribe and suggest, because their young mind is ready to learn new things and fresh techniques. [/quote]