Q&A - PSLE Math

[enoawng]

Dharma:

enoawng:

Mr Ng bought three times as many badges as toy cars and spent $144 in total. He spent $84 more on toy cars than on badges. Given that a toy car cost $10.4 more than a badge, what was the cost of the bagde?

Hi enoawng,

Hope this is useful

http://www.postimage.org/

Hi Dharma,

Isn't your method identical to using algebra if you define \"1 part\" to be the cost of the badge and \"3units\" to the number of badges

My understanding is that algebra is NOT allowed in PLSE. But if you replace algebra with units and parts, does that make it Ok for the examiners.

Please advise since algebra is taught is P6 but is not encourage for use in exams. Thats is my understanding.

Cheers Andrew

[mathsparks]

enoawng:

Hi Dharma,


Isn't your method identical to using algebra if you define \"1 part\" to be the cost of the badge and \"3units\" to the number of badges

My understanding is that algebra is NOT allowed in PLSE. But if you replace algebra with units and parts, does that make it Ok for the examiners.

Please advise since algebra is taught is P6 but is not encourage for use in exams. Thats is my understanding.

Cheers Andrew

Hi enoawng,
My son has been using combi of algebra/model in his p6 practice papers. Algebra IS allowed in PSLE, as long as clear working is shown on how the answer is derived and to define the variables used in the equation eg Let x be the no. of badges bought. Pls clarify with yr child's teacher and share with us his feedback.

[kiasiparent]

James Ang:

There are 1000 lockers in a school with 1000 students. The first student opens all the lockers. The second student closes lockers 2,4,6,8,10 till 1000. The third student changes the state (close opened ones and open closed ones) of lockers 3,6,9,12 till 1000 . The fourth student changes the state of lockers 4,8,12,16 till 1000. How many lockers are opened in the end?

Only 4 students are needed in this question. The other 996 students are redundant. I guess 1000 students is used so that the question will be even harder.

[Dharma]

Hi Andrew,


mathsparks is right.

[enoawng]

Dharma:

Hi Andrew,


mathsparks is right.

Mr Ng bought three times as many badges as toy cars and spent $144 in total. He spent $84 more on toy cars than on badges. Given that a toy car cost $10.4 more than a badge, what was the cost of the bagde?

Ok can anyone confirmed that this method below is allowed and the child will be awarded full marks?

Let N be the number of cars and B the cost of badge

3NB + N(B+10.4) = 144
N(B+10.4) -3NB = 84

Solving above
6NB = 144-84=60
NB=10

From 2nd statement
NB+10.4N-3NB = 84
10.4N= 84+20= 104
N=10; B=$1

Also if we don't use Dharma's method or the algebric method, is there a model method?

Many thanks in advanced.

[kiasiparent]

Algebra are allowed in PSLE.


In fact, last year PSLE requires a lot on the use of algebra to answer a few questions. Other than using algebra, you can also use units and parts but that’s actually algebra in disguise.

Other than that, You probably have to use guess and check.

[Priskhipo]

enoawng:

Dharma:

Hi Andrew,


mathsparks is right.

Mr Ng bought three times as many badges as toy cars and spent $144 in total. He spent $84 more on toy cars than on badges. Given that a toy car cost $10.4 more than a badge, what was the cost of the bagde?

Ok can anyone confirmed that this method below is allowed and the child will be awarded full marks?

Let N be the number of cars and B the cost of badge

3NB + N(B+10.4) = 144


N(B+10.4) -3NB = 84

Solving above
6NB = 144-84=60
NB=10

From 2nd statement
NB+10.4N-3NB = 84
10.4N= 84+20= 104
N=10; B=$1

Also if we don't use Dharma's method or the algebric method, is there a model method?

Many thanks in advanced.

Here is the model method:


http://www.postimage.org/

[enoawng]

Priskhipo:

[


Here is the model method:


http://www.postimage.org/

Thanks. But I think the purple part should be cost of badges and the cost of cars should be purple + blue part, right?

But just wondering if the model method is easier for the boys/girls during examination or is it better to use algebra approach.

Anyone parents has any good advice or experiences?

[Dharma]

tianzhu:

Maybe, I am a much laid back father who just wants my kid to learn sufficient knowledge without subjecting him to additional stress.

Tianzhu,

You contribution to this forum is an encouragement to many other parents to share their knowledge, discuss and solve problems ...all for the sake of our kids. You're an inspiration to others and surely not laid back.

[youngmum]

Hi, can help me solve these 2 questions pls. They are in my boy homework. Thanks.



Q1

When Mrs Lee was 40 years old, her son was twice her daughter’s age. Mrs Lee will be twice her son’s age when her daughter is 28 years old. How old will Mrs Lee be when her daughter is 20 years old? (56 years old)

Q2
At 7am, Car A left Town X for Town Y while Car B left Town Y for Town X. At 3pm, the two cars passed each other. 5 hours later, Car A reached Town Y but Car B was still 150km away from Town X. Find the distance between Town X and Town Y.