PSLE Maths question. How to solve?

[Felipe]

I applaud MOE on not allowing primary school students to use algebra and calculators. These mathematical tools will be used so frequently in our later years that we take them for granted, we know how to use them but we do not know why or how they work and it makes us unable to these tools in our lives.. (take for example differential, integrals, Laplace transformation, Log etc.. )

those mathematical skills i thought are relevant in the engineering industry? maybe not mainstream but if yr an engineer, u should know differentiation and all that right?

[Felipe]

If you can do it with algebra, it's a snap.

 

The giving half to each other thing is just a convoluted way of saying they start out with the same number of sweets and chocolates. Let's say J and K have c chocolates and s sweets each after the exchange.

 

J eats 12 sweets and is therefore left with s-12 sweets and c chocolates.

K eats 18 chocolates and is therefore left with s sweets and c - 18 chocolates.

 

We're given the ratios, putting that into equations we get:

 

(s - 12)/c = 1/7

and

s/(c - 18) = 1/4

 

Solve the simultaneous equations and we get s = 34.

 

Since the orig. no. of sweets K bought is twice that, answer is 68.

 

What I worry about is how the heck do I do it without algebra? I think that's the new (and very stupid) requirement nowadays, if I understood my friend correctly.

 

algebra is an alternative, i don't think it's not allowed, just not encouraged or taught

 

[Milo]

Yup....... until ones reach the age of 16 and hankie pankie starts......

 

 

now sex education starts in sec 1 so i think once they reach 13, their minds start to run wild.

[Babyt]

alot of things we studied we dont apply in our job. even the maths im using daily is simply +-X/ and percentage.

 

of course there are subjects we studied for our knowledge like science and geography but do we really draw contours and graphs now? do we still use benedict solution to test for starch?

 

if only these subjects are non-examinable but on continual assemtment will be better? let it be exam subjects once they chosen to focus on that stream.

 

i absent for my HISTORY O lvl but i dont feel dumb for not knowing my history. i just need to know whats going on in the past but im not keen in memorising the details.

 

and one impt thing, MORAL EDUCATION is a waste of time. you can get A for it but u can still dont practise it haha. ;p

Edited October 11, 2009 by Babyt

[Karchooi]

those mathematical skills i thought are relevant in the engineering industry? maybe not mainstream but if yr an engineer, u should know differentiation and all that right?

 

 

The lower end engineers need to know

The higher ends one make sure his staff knows

[Iisterry]

Piano, ballet, tution, swimming, EM1, EM2, elitism since birth, etc, etc... The trials the childrens are required to go through. My gosh..

 

Our beloved leaders would love nothing more then to have a bunch of "highly-skilled" politically apathetic automatons that will be willing to work for no minimum wage and pay 30% of their salary for thirty years... for affordable chicken coops on a 99 year lease.

 

On a lighter note...

 

 

 

 

 

 

[Sosaria]

The lower end engineers need to know

The higher ends one make sure his staff knows

 

It's not the sums themselves that are very important - but rather the thinking involved in solving the sums. Engineering or the sciences need rational, logical, methodical thinkers and problem-solvers. Maths is one of the subject that enforces such thinking.

 

You'll notice that students weak in these "logical" subjects also have poorer problem-solving skills - in that they come up with grand, fancy designs and "solutions" that cannot be easily manufactured in the real-life environment... (i'm talking about hands-on projects)

Edited October 11, 2009 by Sosaria

[Iisterry]

Its up on yahoo.sg.

 

http://sg.news.yahoo.com/cna/20091010/tap-...pa-231650b.html

 

Parents up in arms again over PSLE Mathematics paper

 

SINGAPORE: The first thing her son did when he came out from the Primary School Leaving Examination (PSLE) maths paper on Thursday this week was to gesture as if he was "slitting his throat".

 

"One look at his face and I thought

[Sosaria]

The highlighted problem is quite tough, for P6 students.

 

Even if straightforward algebra is used for solving via simultaneous equations (and nowadays they're not allowed to use these methods??), it is quite a handful to solve...

[Takumi21]

 

Did we gone through all these during our time??

[Andyngps]

I agree the questions are tougher than during our era. Most of us forgot about using diagrams to solve once we mastered algebra...but in the first place, in relation to this particular problem sum in discussion, how do we know that they have the same no. of S and C to begin with???? Imagine if it's different initially, how the hell can we solve it without algebra within the time allocated?? I tried but I'm using assumption methods and that took quite some time...

Edited October 11, 2009 by Andyngps

[Skunk]

I agree the questions are tougher than during our era. Most of us forgot about using diagrams to solve once we mastered algebra...but in the first place, in relation to this particular problem sum in discussion, how do we know that they have the same no. of S and C to begin with???? Imagine if it's different initially, how the hell can we solve it without algebra??

 

it is different, it was not stated that they're the same.

[Ferraricalifornia]

if everyone really cannot do that question...MOE will moderate it...so don't worry...

 

i took my PSLE some years ago and was taught algebra what..?? though it was basic, i had some friends in my class applying Algebra to solve the questions...

 

you do need a decent level of English Comprehension to comprehend what the math question is asking...

 

for future PSLE students...drop the model idea and go for Algebra instead...it's a much useful method rather that drawing on the paper using models...

 

however, algebra requires maturity to understand...hopefully future PSLE candidates would have matured by the time they take the paper...

[Rayleigh]

 

Did we gone through all these during our time??

 

 

Cos it was mentioned Jim and Ken both gave half.

[Sabretan]

That is the problem w Ministry of Error. They think they very smart, propose change and move forward, but in actual fact are they??? A few years down the road, they make a U-turn going back to the old way, but not admitting it by giving it a new name .

 

 

U think PSLE is bad...wait till ur kids get to JC....u will really pity ur kid...not like A-lvl during my days where u can opt to take 3 A level subjects, siam ECA and participate in ur "own ECA" .

 

I guess it is good in a way coz it trains our kid to be resilient and better time manager. Start training them for the rat race in JC.

[Wind30]

ya lah...

 

there is so many misconceptions in this thread.

 

Algebra is taught in Primary school but NOT simultaneous equations, ie they only have one unknown.

 

You can use ALL methods to solve the questions, including algebra. MOE replied to a ST forum letter officially.

 

my solution using only algebra without simultaneous equation.

 

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frankly I have seen so many variations of such PSLE questions. It is useless looking at answers. The kid must spend 1-3 days thinking about it himself to come to a solution.

 

The "trick" for all these question is that there is no plane of reference. Both subjects are moving at the same time, ie ken and jim both are eating and changing the number of sweets/chocolate. Another variation of such question is when there are two moving objects at different speeds and questions ask you when they cross or meet again.

 

The kid must understand everything is "relative" in this world and with two moving objects, the problem can be made simpler by making one object stationary and transfering the motion to the other object so there is only ONE moving object and the other is reference.

 

For this question, I take Jim as reference and ken as "moving". So if ken + 18 chocolates and minus 12 sweets, he will have identical sweet/chocolate as Jim (1:7 ratio)

 

so you can write a SINGLE variable equation easily once you understand this point.

 

Let x be ken's final sweets.

 

7 * (x-12) = 4x + 18 through inspection. Solving for x and multiplying by 2 will give you the answer.

 

As I always tell my student when I gave primary maths tuition like 7 years ago, the answer is pretty worthless. The method is more impt but the MAIN THING to know is how to derive the method. In this case, it is understanding that one must make something stationary as a reference.

[Sabretan]

Elegant solution, but not one that many students will be able to understand.

[Ender]

Kids are made to grasp the concept of relativity at the PSLE level. Mankind has progress very far..