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Pratakosong

Difficult PSLE 2019 Math Question!

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18 minutes ago, Lala81 said:

yeah. but some people their minds very one track one when doing math. Like me.

Hopefully don't pass down to the 2nd generation. But my girl also can see not much intrinsic ability in math [dead]

Just keep practicing using assessment books. Those assessment books provide step by step methods to solve various type of PSLE questions. Do until no need to think can liao.

Rely on thinking during exam sure cmi one.

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Supersonic
27 minutes ago, Lala81 said:

yeah. but some people their minds very one track one when doing math. Like me.

Hopefully don't pass down to the 2nd generation. But my girl also can see not much intrinsic ability in math [dead]

Need to practice. I also practice with my kids' assessment papers from other schools. My training ground is kiasu parent forum. 🤣. 

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Hypersonic
2 hours ago, Sx4falcon said:

Just keep practicing using assessment books. Those assessment books provide step by step methods to solve various type of PSLE questions. Do until no need to think can liao.

Rely on thinking during exam sure cmi one.

Haha 不是天才的命。。。

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Supersonic
5 hours ago, Lala81 said:

Haha 不是天才的命。。。

For average kids  is no choice one. Have to practice and practise. Every week, my girl will do 3 assessment paper from other school. Those you can buy from neigborhood shops in stack. But they don't have solutions, only answers.  But no problem, I post those questions at kiasuparent for those I cannot solve.

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10 hours ago, Ody_2004 said:

Yah need some thinking.. i solve by algebra.. but seem not allow or not in their syllabus 

For a twelve years old who under exam stress and time constrain maybe find it tough.. see the diagram they oredi goes.. WTF.. simi lai ei..

I strongly agree, we as adults find it easy because we are not subject to all the exam stress and timed conditions, i can't imagine what is going through the kids minds when they are faced with such a question in the PSLE, even more so when they expect to use "Pi" in circles questions and it is not required here...

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4th Gear (edited)

After staring at this for a long time, I realized there is a shortcut.

Diameter of left top semi-circle is 22+unknown.

Diameter of left bottom semi-circle is unknown+12+another unknown.

Since the first unknown is shared, we can exclude it, so the second part becomes 22 = 12 + unknown.

That unknown is hence 10cm.

From there, we can find the diameter from the third semi-circle as both sides are symmetrical: 10+16+10.

Algebra in disguise, but is logic-based solution.

Edited by Nhyone

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6th Gear (edited)
On 9/28/2019 at 7:33 AM, Pratakosong said:

My son's exact working in PSLE (im very very surprise he could do this!!!!!!)

let the unknown distance be X and Y

2X + 16 = X + 12 + Y

2X + 4 = X + Y

X + 4 = Y

2X + 16 = X + 4 + 22

X = 10

Diameter = 10 + 16 + 10

= 36 cm

 

Edited by Hiphiphoray
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6th Gear (edited)
On 9/28/2019 at 7:42 PM, Pratakosong said:

my son got 17a & B correct but left 17c blank.....Hiaz (he told me the whole PSLE exam P1 & P2, this is the only question he don't know...…..im like SURE BOR!!!!)  LOL!!!

My simplified version for 17c

        W      (diff)      G      Total

F1     1         1          0        1     (1x1)

F2     1         2          3        4     (2x2)

F3     6         3          3        9     (3x3)

F4     6         4          10      16  (4x4)

 

Since its a repeat pattern.....1 & 1 , overlapping 3 & 3. 

Grey F5 must be a overlapping 10 & 10

Since F5 total is a 5x5 = 25.

Using basic model, F5 white must be 25-10 = 15

Now for F250...……..

Basically you have to test whatever self-invent formula on F3 & F4....if it works then proceed to find F250.

Something like from Total how to get white, or from grey how to get total...….along this line (that's what I taught my son)

Just test on F3 & F4...don't test on F2 cos its not accurate.

Now using simple model to test on F3 & F4 & F5

U can see F3 is actually total 3x3 with diff 3.

hence F250 will be 250x250 = 62500 with diff 250.

using model, you will get 31125 & 31375 (grey / white, or  white / grey)

Which is which ?????

Go back to F3, F4, F5.....see it like a model

F3   White - Big, Grey - Small

F4  White - Small, Grey- Big

F5 White - Big, Grey - Small

Its actually a sequence !!!!!!!

Odd number - Grey is ALWAYS small

Even number - Grey is ALWAYS big

Hence for F250, Grey is 31375. White is 31125

% of Grey = 50.2 percent. 

 

 

 

Edited by Hiphiphoray
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On 9/28/2019 at 1:03 PM, Lala81 said:

Haha 不是天才的命。。。

Just download the CA1, SA1, SA2 papers from the internet.

Search and you will find it.

And throw in tons of time and effort into writing the worked solutions properly and systematically. (you need lots of patience and perseverance for this)

Don't just see their suggested worked solutions....its crap!!! DIY via assessment books and YOUTUBE videos and make it as simplified as possible. Easy to understand

Then pass on the skill to your kid.

I did it from ground zero when my boy was P4...……….U can do it too!!!! 

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Hypersonic

I guess the days of knowing how to answer everything in PSLE and only getting wrong for careless mistakes are gone... [:p]

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Hypersonic (edited)

Year in year out, very year come PSLE will be the same. Got ppl say so easy, got ppl cry, got ppl complain paper very tough, got parents cannot do the paper and question even parents cannot do, how to expect a 12 yr old kid to do...

seriously, after so many years, I still dont really bother with the after effect. What sld have been done before the exam sld have all been done before the exam.  Exam papers are not meant to fail students, but it cannot be set in a way that every student gets 100% right? 

60% of the paper is set in a way that as long as you pay attention in class and do your work, you can answer. Another 20% is set of a higher standard to reward those are more working and do a lot of other practices. Last 20% are usually outside the standard, this is where they separate the top students from the avg, usually need some thinking. 

Its perfectly normal to have some questions that most students cannot answer, no big deal lor. 

It is always the parents who are making the noise. Give the kids a break lah, they have all the time they have to prepare for the exam, go to the exam, do it, and let it be.  Let them go through the paper, let it go, and move on to the next paper.  

Its PSLE, its not the end of the world.  Cannot do one or two  questions, so what??? [laugh][laugh][laugh]

Edited by Tianmo
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44 minutes ago, Lala81 said:

I guess the days of knowing how to answer everything in PSLE and only getting wrong for careless mistakes are gone... [:p]

I think the PSLE is now testing the student's ability to apply the techniques and skills they have learnt to a couple of unfamiliar and unique questions.

Can't have all the questions being so predictable that it becomes meaningless. After all i think MOE will moderate the marks if there is a too drastic change in proportion of students scoring each of the grades.

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Hypersonic
29 minutes ago, Tianmo said:

Year in year out, very year come PSLE will be the same. Got ppl say so easy, got ppl cry, got ppl complain paper very tough, got parents cannot do the paper and question even parents cannot do, how to expect a 12 yr old kid to do...

seriously, after so many years, I still dont really bother with the after effect. What sld have been done before the exam sld have all been done before the exam.  Exam papers are not meant to fail students, but it cannot be set in a way that every student gets 100% right? 

60% of the paper is set in a way that as long as you pay attention in class and do your work, you can answer. Another 20% is set of a higher standard to reward those are more working and do a lot of other practices. Last 20% are usually outside the standard, this is where they separate the top students from the avg, usually need some thinking. 

Its perfectly normal to have some questions that most students cannot answer, no big deal lor. 

It is always the parents who are making the noise. Give the kids a break lah, they have all the time they have to prepare for the exam, go to the exam, do it, and let it be.  Let them go through the paper, let it go, and move on to the next paper.  

Its PSLE, its not the end of the world.  Cannot do one or two  questions, so what??? [laugh][laugh][laugh]

No lah. Our time bit different. Just show how times have changed. This kinda questions would have been math olympiad question during my time. 

Got good got bad. Just need a correct mindset to be instilled from parents and teachers so that some kids don't get demoralised. 

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Hypersonic
15 minutes ago, Pratakosong said:

I think the PSLE is now testing the student's ability to apply the techniques and skills they have learnt to a couple of unfamiliar and unique questions.

Can't have all the questions being so predictable that it becomes meaningless. After all i think MOE will moderate the marks if there is a too drastic change in proportion of students scoring each of the grades.

No lah. Just comparing to my time. Generally I approve of the way they teach math in school. Like even though my girl is p1.

There is a strong lesson plan in place. They really try hard to teach logic and abstract reasoning which was sorely missing when I was growing up. We were just taught to be calculators rather than use reasoning. 

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Hypersonic
11 minutes ago, Lala81 said:

No lah. Our time bit different. Just show how times have changed. This kinda questions would have been math olympiad question during my time. 

Got good got bad. Just need a correct mindset to be instilled from parents and teachers so that some kids don't get demoralised. 

You RI kids standard cannot understand the mass market school standard one lah...[laugh]

Our time, parents not so kiasu so standard not so high, as the years goes by the standard gets higher and higher because the usual standard questions are getting too easy for most students, thats why you have math olympiad questions now.  And by the standard these days,  olympiad questions would likely be the top 20% of the paper.. 

Teachers dont usually want to tell students how the papers are segmented, but parents need to understand and not expect their kids to be able to answer all the questions mah. Personally I see so many young kids burn out too early because of parents expectation. 

And I dont think the question TS stated is really difficult, in fact I think it is quite normal if you use the model method by @Ender, which is what the schools have been teaching. I have seen many more difficult questions at school level before. 

For the question, it appears difficult because someone complained it is so tough that many kids cannot do, and so  we starts to put up our tough questions wall and looks at it from the difficult angle. 

I am no maths expert, but this question just move all the semi circle to the left, and numbers to the right, remove 2 full circles to get to the lowest form,  24 + D = 60, so D is 36 lor. 

Last time I sell shoes to schools, got one time one parent came and say,  你们的鞋很滑, 很多人穿了跌倒。 My brother ask her, 你们姓很,你儿子叫多人是吗? That aunty hear liao kept quiet.  My point is sometimes, parents make a big hoohay out of a question their kid cannot answer just to make themselves feel better only, may not be that bad as a whole actually..[laugh][laugh][laugh]

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Hypersonic
34 minutes ago, Lala81 said:

No lah. Just comparing to my time. Generally I approve of the way they teach math in school. Like even though my girl is p1.

There is a strong lesson plan in place. They really try hard to teach logic and abstract reasoning which was sorely missing when I was growing up. We were just taught to be calculators rather than use reasoning. 

Yah, now they are trying to teach more logic and apply, but not all teachers can teach logic and apply lor.  Many schools are not really ready to use application to teach yet also. Your girl mayb lucky to be the fist few batches, those P4-P6 will be those trap in between, but bopian lor, wrong time wrong place for them.....[laugh][laugh][laugh]

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Twincharged
On 9/28/2019 at 9:08 AM, Lala81 said:

I understand both solutions but not ender's. Honestly if i met this in an exam, i probably couldn't answer it without preparation. Math/spatial logic not my strongest suit.

Because you have no primary school going children, otherwsie you would know how to solve these type of questions. I remember parents have to attend their math solutuoning class when their kids are  at primary 4.  You cannot try to use algebra to solve it because primary students have not taught  algebra. 

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