Q&A - P3 Math

[shurley197323]

Hi. thks for all the answer. But all this method is not taught in my girl’s school yet. How about yours ? They donot know "xy" and "1 or 2 units"

Do yr child in P3 already know that in school ?

[en107rn.01056yahoo.01056com.01056sg]

[quote]Hi. thks for all the answer. But all this method is not taught in my girl's school yet. How about yours ? They donot know \"xy\" and \"1 or 2 units\"

Do yr child in P3 already know that in school ?[/quote]Taught in dd school. Should be as around P3 level. I'm not sure but some question take a while for me to think.

Not taught at ds school but he is in P2.

[Tang]

There is a new P4 Maths Blog for P4 pupils. You may want to make full use of it.


http://p4mathsquestions.blogspot.com/

[shurley197323]

Thks. It very useful. Pls let me knw when there is a site for P3 too.

[Suz855]

[Moderator's note: Topics merged.]


Hi,

Can the below PS posted on P4Maths be solved using model, pls help, thanks :?

Mrs Raju bought a sack of rice which weighed less than 50kg. If she packed the rice into bags of 5kg each, she would have 3kg of rice left. If she packed it into bags of 7kg each, she would have 4kg of rice left. How many kg of rice did Mrs Raju buy?[/img]

[James Ang]

Suz855:

Hi,


Can the below PS posted on P4Maths be solved using model, pls help, thanks :?

Mrs Raju bought a sack of rice which weighed less than 50kg. If she packed the rice into bags of 5kg each, she would have 3kg of rice left. If she packed it into bags of 7kg each, she would have 4kg of rice left. How many kg of rice did Mrs Raju buy?[/img]

this question use a listing can do

multiple of 5 add 3
8, 13, 18, 23, 28, 33. 38. 43, 48

multiple of 7 add 4
11, 18, 25, 32, 39, 46

answer is 18

[Suz855]

I knew how to get the answer, I'm looking for model approach to solve this question. Anyone, thanks :oops:

[James Ang]

Suz855:

I knew how to get the answer, I'm looking for model approach to solve this question. Anyone, thanks :oops:

making a list is a heuristics method, it does not make sense to solve a simple question with a model.

A simple question should not be \"forced\" into other complex solving methods; just for the sake of it as it defeats the purpose of solving maths problems efficiently.

Let me tell a fictional story;

When the American astronaunts went to outer space, they discovered that their ball point pen did not work as there is no gravity in space. (try writing with a pen upside down, it does not work). The American astronaunts brought the problem back to Earth and the scientists spent years and millions of dollars to come up with a sleek and amazing pen that can write without the use of gravity. They tested it in outer space to perfect their invention and finally declared to the whole world that the new invention is a breakthrough and Man can now write in outer space as a result of their cutting edge research.

The Russian astronaunts faced the same problem when they went to outer space and before the Americans invented the amazing no gravity pen, the Russian astronaunts worked around the problem and came up with using the PENCIL to write in outer space, thus saving tons of money and time effort.

[Dharma]

Suz855:

I knew how to get the answer, I'm looking for model approach to solve this question. Anyone, thanks :oops:

Hi Suz855,

James is right to choose to list in order to solve the problem in the easiest manner. You don't need to use models to solve all problems and not all problems can be solved easily by the model method.

Some common heuristics for problem solving include
1. Draw a diagram
2. Make a list.
3. Guess and check.
4. Find a pattern
5. Before and after
6. Working backwards
7. Using equations
8. Restating a problem
9. Using branch method
10. make suppositions
etc

You need to select the suitable heuristics that can be applied to the qn asked.

[James Ang]

Dharma:

Suz855:

I knew how to get the answer, I'm looking for model approach to solve this question. Anyone, thanks :oops:

Hi Suz855,

James is right to choose to list in order to solve the problem in the easiest manner. You don't need to use models to solve all problems and not all problems can be solved easily by the model method.

Some common heuristics for problem solving include
1. Draw a diagram
2. Make a list.
3. Guess and check.
4. Find a pattern
5. Before and after
6. Working backwards
7. Using equations
8. Restating a problem
9. Using branch method
10. make suppositions
etc

You need to select the suitable heuristics that can be applied to the qn asked.

Thanks Dharma. Anyway I like your nick.

Also let me explain in simple English what the word \"heuristics\" mean as many adults think that it means something \"chim\". \"Heuristics\" means \"rules of thumb\" or quick and logical rules to solve a problem usually a patterned one (such as the astronaut's problem in above story).

A good example of heuristics is the patterned problem; find the sum of 1+2+3=....+998+999+1000.

The original story was that this arithmetic problem (AP) was given to a group of students and the teacher was surprised that a student was able to solve it in less than 10 secs, and the student explained to the teacher that what he did was to add the first and last numbers together, second and second last numbers together until they are all paired up. Then multiply the same answer by half the number occurrence. That is (1+1000) x 1000/2 = 500500.

This story was told by an Add Maths teacher who taught me many years ago in VS, and his story telling style helped me understand the logic and purpose of solving Arithmetic and Geometric Problems (AP,GP). Such heuristics are very simple, effective but powerful, rather than just memorising maths methods, so heuristics (or rules of thumbs) are really higher order thinking skills that students can master. (imagine, that these heuristics are derived from Upper sec Add Maths old topics taught years ago)