2009 Maths Question which Adult also duno!


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melvin

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#1
This year PSLE!

From Yahoo Sg:

Jim bought some chocolates and gave half of it to Ken. Ken bought some sweets and gave half of it to Jim. Jim ate 12 sweets and Ken ate 18 chocolates. The ratio of Jim’s sweets to chocolates became 1:7 and the ratio of Ken’s sweets to chocolates became 1:4. How many sweets did Ken buy?"




Anyone? Me still trying!:sweat:
 

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night86mare

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#3
simple simultaneous equation.

assume jim buys c chocolates, ken buys s sweets.

at the end, jim will have c/2 chocolates, ken will have c/2 - 18 chocolates
at the end, jim will have s/2 -12 sweets, ken will have s/2 sweets

c/2 = 7(s/2 - 12) = 7s/2 - 84 --- (1)
c/2 - 18 = 4(s/2) = 2s --- (2)

from (2): c/2 = 2s + 18 --- (3)

sub (3) into (1)

2s + 18 = 7s/2 - 84
so 102 = 3/2 s

s = 68
c = 308

checked the answer is correct;

jim has 154 chocolates, ken has 154- 18 = 136 chocolates
ken will have 34 sweets, jim will have 22 sweets

154/22 = 7
136/34 = 4

QED
 

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#4
isn't this the maths question from the PSLE everybody was complaining about...

i replace the choc and sweet with X and Y then from there form equations... thats how i do it, or maybe there is a easier way i dunno... anyway these questions are more towards Sec sch standard...

i think i better start to prepare myself in the future, wait my kid ask me i dunno... :bsmilie:
 

melvin

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#5
simple simultaneous equation.

assume jim buys c chocolates, ken buys s sweets.

at the end, jim will have c/2 chocolates, ken will have c/2 - 18 chocolates
at the end, jim will have s/2 -12 sweets, ken will have s/2 sweets

c/2 = 7(s/2 - 12) = 7s/2 - 84 --- (1)
c/2 - 18 = 4(s/2) = 2s --- (2)

from (2): c/2 = 2s + 18 --- (3)

sub (3) into (1)

2s + 18 = 7s/2 - 84
so 102 = 3/2 s

s = 68
c = 308

checked the answer is correct;

jim has 154 chocolates, ken has 154- 18 = 136 chocolates
ken will have 34 sweets, jim will have 22 sweets

154/22 = 7
136/34 = 4

QED

:thumbsup: What if the kid duno simultaneous equation? sure they are not taught simultaneous equation in P6? Any other easier way?:think:
 

night86mare

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:thumbsup: What if the kid duno simultaneous equation? sure they are not taught simultaneous equation in P6? Any other easier way?:think:
use model drawing.

it is just a stupid way of doing simultaneous equations algebra.. but it works too.

that's what we had to do in pri 6..

anyways, the main issue is not getting out the answer, the main issue is that the calculations are so tedious, easy to make mistake. they allowed to use calculators?

i've seen some recent pri 6 school papers, they are loaded with this type of questions, it really shouldn't be an issue as to doing it, rather about making mistake. i don't know their syllabus though.. :) but i'm sure if so many papers had it, it was taught in some way.
 

melvin

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#8
isn't this the maths question from the PSLE everybody was complaining about...

i replace the choc and sweet with X and Y then from there form equations... thats how i do it, or maybe there is a easier way i dunno... anyway these questions are more towards Sec sch standard...

i think i better start to prepare myself in the future, wait my kid ask me i dunno... :bsmilie:
Nowadays it is rather common for parents to duno how to do their children school work! Like my friend (dipolma) cant even score 100% of her son's P6 Maths!

Standard high high!:sweat:
 

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#9
simple simultaneous equation.

assume jim buys c chocolates, ken buys s sweets.

at the end, jim will have c/2 chocolates, ken will have c/2 - 18 chocolates
at the end, jim will have s/2 -12 sweets, ken will have s/2 sweets

c/2 = 7(s/2 - 12) = 7s/2 - 84 --- (1)
c/2 - 18 = 4(s/2) = 2s --- (2)

from (2): c/2 = 2s + 18 --- (3)

sub (3) into (1)

2s + 18 = 7s/2 - 84
so 102 = 3/2 s

s = 68
c = 308

checked the answer is correct;

jim has 154 chocolates, ken has 154- 18 = 136 chocolates
ken will have 34 sweets, jim will have 22 sweets

154/22 = 7
136/34 = 4

QED
the smart ones will skip this question.
 

melvin

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#10
Fully agree with you. Wonder MOE is testing lang or maths...kekeke. I've problem with P4 maths
:bsmilie: To me they are trying to differentiate who the Elites are or rather sperate the Elites from the normal students!:sweatsm:
 

Jul 23, 2005
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#12
:bsmilie: To me they are trying to differentiate who the Elites are or rather sperate the Elites from the normal students!:sweatsm:
They are trying to differentiate those who studied sec school stuff while in primary school.
Personally this does not really mean those who can answer the questoin are elite.
I recall in my class, those 'smart kids' who studied ahead did well in primary & secondary school, then most of them fast the harsh reality that they are just the same or even not as good as their peers when they are in tertiary level and at work.
 

Old Boy

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#13
Algebra solution is not taught in primary school but need to use model and it's tedious. Only way is to teach them algebra on your own and then tell them to provide model ( table )answers after they find the answer through algebra. Still the child understand the model concept but answer the question in shorter time.:bsmilie:
 

shunzi

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#14
gosh.....

now i know why the aunties in my office are making a big fuss out of this. :bsmilie:
 

Prismatic

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#18
Honestly, I don't see what the big hoohah is about the exams. If it's really difficult, then results will just fall across the cohort. It's not as if there is any unfairness in the exams ( like some people have an advantage). Maybe it's just parents who are feeling embarassed because they can't do the questions.:bsmilie:
 

Apr 15, 2008
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#19
the smart ones will skip this question.
Actually, you have a point, if this is really the hardest question in the paper, skimpily doing it for a few 'working marks' and answering the rest will still earn you a A grade.

I wonder if these qns are really representative of the entire paper's difficulty :think:


P.S- I find it kinda dumb that algebra isn't allowed in the PSLE though :sticktong
 

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