Help needed for primary math Q!!!

[I-LOVE-CARS]

Think round off also wrong lol

 

Sorry lah, maths was my worst subject in Primary Schools days

 

PSLE Grades:

English: A

Maths: C

Chinese: B

Science: B

Total Score: 193

 

 

[I-LOVE-CARS]

i really wonder why they dont allow algebra.

 

its a more practical way and easier to understand and it can be applied when they hit secondary school.

 

this diagram or tikam method is a waste of time.

 

Guess and Check was the worst method to use for PSLE, as it takes out alot of ur time, but no choice, cos Primary School no Algebra.. :angry: I still remember i nearly cried when i saw the Maths PSLE Paper 2..

[Thaiyotakamli]

Sorry lah, maths was my worst subject in Primary Schools days

 

PSLE Grades:

English: A

Maths: C

Chinese: B

Science: B

Total Score: 193

No wonder haha, good english huh

[Redboy]

Badmonton club in a school spent $681 to buy 50 t-shirts n shorts for its members. Each t-shirt cost $12 n each pair of short cost $15, how many t-shirt did the club buy?

 

Bros, help me with this math qn, my P4 cousin ask me n i dont know the answer lol

 

bro, use this method:

 

if there are 50 t shirts and shorts in total, assume that the club bought 25 t shirts and 25 pair of shorts.

 

25 x 12 = $300

25 x 15 = $375

 

$300 + $375 = $675 (does not tally with $681 yet)

So need to increase the total price by buying more of the expensive item & buying less of the cheap item.

 

Imagine, if the club replaces 1 T shirt with 1 pair of shorts, they pay $3 more.

So if the club replaces 2 T shirts with 2 pairs of shorts, they pay $3x2=$6 more.

 

Hence, now, they are not buying 25 T shirts and 25 pair of shorts, so to tally with $681, they have to return 2 T shirts and buy 2 pairs of shorts to replace.

 

Thus, now they are buying 23 T shirts and 27 pair of shorts. Problem solved.

[Redboy]

Guess and Check was the worst method to use for PSLE, as it takes out alot of ur time, but no choice, cos Primary School no Algebra.. :angry: I still remember i nearly cried when i saw the Maths PSLE Paper 2..

 

thing is, Pri Sch students learn algebra but only in Primary 6

 

Until now, still dun understand why they dun let Pri Sch students learn it earlier

[Rayleigh]

Badmonton club in a school spent $681 to buy 50 t-shirts n shorts for its members. Each t-shirt cost $12 n each pair of short cost $15, how many t-shirt did the club buy?

 

Bros, help me with this math qn, my P4 cousin ask me n i dont know the answer lol

 

 

your cousin needs to use guess and check method. This method was taught in Pri 3. The control parameters are 50 units and $681

[PPeripheraL]

i believe he won't be marked wrong for using algebra method as well. and algebra is relatively easier to understand and easier to solve.

[Thaiyotakamli]

your cousin needs to use guess and check method. This method was taught in Pri 3. The control parameters are 50 units and $681

Long way to do is really troublesome, y they dont allow algebra?? Lol

[Thaiyotakamli]

Thanks bro, it really help alot!

[Happily1986]

 

i think i left out one step that is using $581 to divide by $27 to get 25.2222. basically my method is model + guess and check.

[Rayleigh]

Long way to do is really troublesome, y they dont allow algebra?? Lol

 

Algebra doesn't provide a pictorial representation of the problem. Solving abstract math using modelling provides an elegant solution where a single glance gives you an instance appreciation of the problem.

[Thaiyotakamli]

i think i left out one step that is using $581 to divide by $27 to get 25.2222. basically my method is model + guess and check.

Thx for reply bro but i use shorter solution n i dont think the teacher will understand lol

 

Price diff: 15-12 = $3

12x50=600

Remainder: 681-600= 81

Number of short: 81/3= 27 pairs

Shirt: 50-27= 23 pieces....

 

 

Understand? I even see my working also like bochupp haha anyway just one question, so let teacher go n figure it out... My task is done :)

[Thaiyotakamli]

Algebra doesn't provide a pictorial representation of the problem. Solving abstract math using modelling provides an elegant solution where a single glance gives you an instance appreciation of the problem.

But with algebra its better to think, to imagine as using the assumption which make work easier...

I think primary nvr teach algebra cos they want students to know how the answer originated from, so using long way

[Nightsky]

Thx for reply bro but i use shorter solution n i dont think the teacher will understand lol

 

Price diff: 15-12 = $3

12x50=600

Remainder: 681-600= 81

Number of short: 81/3= 27 pairs

Shirt: 50-27= 23 pieces....

 

 

Understand? I even see my working also like bochupp haha anyway just one question, so let teacher go n figure it out... My task is done :)

 

No, your method is actually correct. It is called the supposition method, and is considered a far more 'high class' method than guess and check.

 

For those who think that guess and check / trial and error / combination models are still being used in PSLE, i'm sorry to say at that standard nowadays, your A* can forget about it - at most you will get a B, or if you are lucky and bell-curve saves you, an A.

 

Kids are being taught guess and check in primary 3, but the supposition method is used in primary 4 onwards - that is if the teacher bothers to teach that method to the students, or if the student is in a good enough school - remember that many old teachers find it challenging to keep up with contemporary heuristics used nowadays.

 

The reason why algebra is not taught in primary school is because of the 21CC initiative by MOE, as well as the focus for mathematics on metacognition / visualisation / pattern recognition centric question types.

 

[Shawntai]

Hmm.... My answer different lei....

 

23 pairs( t-shirt & short)-- $621

plus 5 t-shirts -- $60

 

So total add up will be 621 + 60 = 681

 

The question nvr say which one is more or less.

most of the tshirt also funny, so best is get the most pair and in the same time use up all the money given.

 

That is my answer . 28 t-shirt & 23 short

[Thaiyotakamli]

Hmm.... My answer different lei....

 

23 pairs( t-shirt & short)-- $621

plus 5 t-shirts -- $60

 

So total add up will be 621 + 60 = 681

 

The question nvr say which one is more or less.

most of the tshirt also funny, so best is get the most pair and in the same time use up all the money given.

 

That is my answer . 28 t-shirt & 23 short

Wad??? Lol can be 2 answer, y i never think of that lol

[Jp66]

Hmm.... My answer different lei....

 

23 pairs( t-shirt & short)-- $621

plus 5 t-shirts -- $60

 

So total add up will be 621 + 60 = 681

 

The question nvr say which one is more or less.

most of the tshirt also funny, so best is get the most pair and in the same time use up all the money given.

 

That is my answer . 28 t-shirt & 23 short

but the question already stated total 50 t-shirt & short, your total is 51.

[Jp66]

Shorts cost $3 more than T-shirt. Total spent $681.

 

If both cost the same at 12, then 50 pcs will cost 12*50 = 600.

Balance 81.

Since each shorts cost extra $3, Divide 81 by 3= 27.

 

Therefore, T-shirt is 23, short is 27.

Total $681, the one place is $1

The one place for short is either $0 or $5.

The one place for t-shirt is always even number (multiple of 2), so number of t-shirt should be 3, 13, 23, 33 or 43.

 

Using guess and check method,

 

3 t-shirt ($36), 47 short ($705), total $741 (Wrong)

 

13 t-shirt ($156), 37 short ($555), total $711 (Wrong)

 

23 t-shirt ($276), 27 short ($405), total $681 (Correct)