## Lower Secondary Mathematics

PSLE marks the graduation of Primary school students and their entry into Secondary schools as teenagers. Discuss all issues about Secondary schooling here.

### Re: Lower Secondary Mathematics

tankee wrote:
tankee wrote:Kindly help with the following qn, thanks.
Without drawing the graphs, explain why the simultaneous equations
y = -2x + 5
y = 2x - 33
have no solution

Hi, is there any typo error in the question?

I am able to find the solution, which is x= 9.5 and y=-14.

......

likewise. But since it has been a while, I thought better seek help to be sure just in case it isn't a typo.

thanks.

A quick sketch of the graph will show that there is a solution.
I believe that it's a typo, and it probably is on either of the gradient/x-coefficient of the 2 equations.

The explanation should be because the gradient of the lines are the same (-2 OR 2; unable to determine due to typo), that means the 2 equations are parallel to each other, and therefore will never meet each other. => no solutions.

Jmaths.SG
YellowBelt

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### Re: Lower Secondary Mathematics

Hi

Can someone help on this question? (Without using calculator, show the workings)

TeaBoh
OrangeBelt

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### Re: Lower Secondary Mathematics

Is there a Math expert who can explain why the solution of the question:
In 2006, the price of one litre of petrol was \$2.30. If the price of petrol in 2006 was 15% less than the price in 2005, calculate the price of one litre of petrol in 2005:
Is as follows:
Price of 1 litre of petrol in 2005 = 100/85 X 2.3 = \$2.71

My question is: why is it 100/85 ( as in 100 divided by 85)?

Thanks so much!!! Really appreciate clarification on this

blissful mummy
YellowBelt

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### Re: Lower Secondary Mathematics

blissful mummy wrote:Is there a Math expert who can explain why the solution of the question:
In 2006, the price of one litre of petrol was \$2.30. If the price of petrol in 2006 was 15% less than the price in 2005, calculate the price of one litre of petrol in 2005:
Is as follows:
Price of 1 litre of petrol in 2005 = 100/85 X 2.3 = \$2.71

My question is: why is it 100/85 ( as in 100 divided by 85)?

Thanks so much!!! Really appreciate clarification on this

For questions on percentage, one has to be very clear of which quantity is equivalent to 100%, usually it is the original quantity or the quantity that we are comparing with will be 100%.
In this question,we are comparing the price of one litre of petrol in 2006 to the price in 2005. Hence 2005 price is equivalent to 100% and 2006 being 15% lesser, will be 85%.
Thus,2006: 85% - \$2.30
2005:100%-\$2.30/85x100=\$2.71

PiggyLalala
KiasuGrandMaster

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### Re: Lower Secondary Mathematics

Hi Piggylalala, really appreciate your clear and concise explanation, I get it now! Thanks v much for your kind help, really appreciate your time Have a lovely week ahead!

blissful mummy
YellowBelt

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### Re: Lower Secondary Mathematics

blissful mummy wrote:Hi Piggylalala, really appreciate your clear and concise explanation, I get it now! Thanks v much for your kind help, really appreciate your time Have a lovely week ahead!

Glad that I could help. U have a nice week ahead too.

PiggyLalala
KiasuGrandMaster

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### Re: Lower Secondary Mathematics

Sec 1 math has quite a fair bit of algebra , which I prefer.
Ds told me his class mate use psle model method to solve the story sum
Teacher gave that boy Zero ! Recall back, pri kids spends so many yrs
On hateful model , ended up not allowed in sec sch - Wat happen to math syllabus ? Pri n sec no linkages , why make the pri kids " suffer " so much nei

MyPillow
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### Re: Lower Secondary Mathematics

Need help on this question.

The price of a sofa is \$x. A man buys the sofa on hire purchase according to the following terms: a downpayment of 25% and the remaining to be paid in monthly installments over 30 months at a simple interest rate of 12% per annum. Given that his monthly instalment is \$52, find the value of x.

cftan
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### Re: Lower Secondary Mathematics

cftan wrote:Need help on this question.

The price of a sofa is \$x. A man buys the sofa on hire purchase according to the following terms: a downpayment of 25% and the remaining to be paid in monthly installments over 30 months at a simple interest rate of 12% per annum. Given that his monthly instalment is \$52, find the value of x.

Please let us know if you need further explanation, our team of ex IP school/RGS/NYGH teachers are here to support you.

GreenBelt

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### Re: Lower Secondary Mathematics

MyPillow wrote:Sec 1 math has quite a fair bit of algebra , which I prefer.
Ds told me his class mate use psle model method to solve the story sum
Teacher gave that boy Zero ! Recall back, pri kids spends so many yrs
On hateful model , ended up not allowed in sec sch - Wat happen to math syllabus ? Pri n sec no linkages , why make the pri kids " suffer " so much nei

Hi Mypillow,

There is a link between model and algebra actually. To certain extent, model is indeed a simplified pictorial presentation of algebra.

Primary school students cannot understand algebra well as it is quite abstract. So we use model approach to help students in understanding and visualising the questions.
However, model approach has its limitation as it is a simplified substitution of algebra. Therefore, teachers in secondary school insist that the students need to learn the more advanced and proper algebra, rather than always stick to model.

Cheers!