Q&A - PSLE Math

[mummyjoyce]

Very good links… must print out and let my DD practise! Thank you for doing this.

[meeyah]

Thanks for sharing…The problem sums are really difficult. Can someone sharing the workings on how they arrive the answers? Hehehee…not sure whether I am being greedy to ask for more.

[CoffeeCat]

I believe the above 3 replies was shifted from this thread

Q&A - PSLE Maths - Highlights ONLY
http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=9494

meeyah:

Thanks for sharing...The problem sums are really difficult. Can someone sharing the workings on how they arrive the answers? Hehehee...not sure whether I am being greedy to ask for more.

I think you need to specify the problems you have trouble with and hopefully some math guru can add on in that thread for future reference. The 2009 questions are being done countless times in the thread i specified in the post there.

[tianzhu]

[quote]Well,ratio problems are supposed to be solved by ratio.I love using ratio but i'm always stuck at challenging questions that involve ratio.One quick(inaccurate) example is this: The marbles that A and B has is in the ratio 6:7. Then,124 marbles were added to the total and the ratio became 2:3.How many marbles were there at first? These kind of questions are common and its almost impossible to solve using model. If your dd knows how to use ratio to solve such challenging problems,then your dd should be alright if she wants to use model now as she still have the \"skills\" to apply the ratio method if she needs it.However,if she cannot solve using ratio,then she may face difficulty with the challenging questions.[/quote]
Hi

I picked up this quote from the thread, Tips for improving in PSLE. It was from a member called livewith_vanilla.

I think the question she posed is a pretty interesting one, it involves two changed quantities, but the number(124) involved in the transaction is lumped into one lot instead of two different portions.

The marbles that A and B has is in the ratio 6:7. Then,124 marbles were added to the total and the ratio became 2:3.How many marbles were there at first?

Have fun.
Best wishes

[Vanilla Cake]

tianzhu:

[quote]Well,ratio problems are supposed to be solved by ratio.I love using ratio but i'm always stuck at challenging questions that involve ratio.One quick(inaccurate) example is this: The marbles that A and B has is in the ratio 6:7. Then,124 marbles were added to the total and the ratio became 2:3.How many marbles were there at first? These kind of questions are common and its almost impossible to solve using model. If your dd knows how to use ratio to solve such challenging problems,then your dd should be alright if she wants to use model now as she still have the \"skills\" to apply the ratio method if she needs it.However,if she cannot solve using ratio,then she may face difficulty with the challenging questions.

Hi

I picked up this quote from the thread, Tips for improving in PSLE. It was from a member called livewith_vanilla.

I think the question she posed is a pretty interesting one, it involves two changed quantities, but the number(124) involved in the transaction is lumped into one lot instead of two different portions.

The marbles that A and B has is in the ratio 6:7. Then,124 marbles were added to the total and the ratio became 2:3.How many marbles were there at first?

Have fun.
Best wishes[/quote]Hi Uncle Tianzhu,
There seems to be more than one possible correct answer for this question. I have posted a reply to \"livewith_vanilla\" to seek her clarification for this \"One quick(inaccurate) example is this:.....\"

[tutortamil]

Vanilla Cake:

tianzhu:

[quote]Well,ratio problems are supposed to be solved by ratio.I love using ratio but i'm always stuck at challenging questions that involve ratio.One quick(inaccurate) example is this: The marbles that A and B has is in the ratio 6:7. Then,124 marbles were added to the total and the ratio became 2:3.How many marbles were there at first? These kind of questions are common and its almost impossible to solve using model. If your dd knows how to use ratio to solve such challenging problems,then your dd should be alright if she wants to use model now as she still have the \"skills\" to apply the ratio method if she needs it.However,if she cannot solve using ratio,then she may face difficulty with the challenging questions.

Hi

I picked up this quote from the thread, Tips for improving in PSLE. It was from a member called livewith_vanilla.

I think the question she posed is a pretty interesting one, it involves two changed quantities, but the number(124) involved in the transaction is lumped into one lot instead of two different portions.

The marbles that A and B has is in the ratio 6:7. Then,124 marbles were added to the total and the ratio became 2:3.How many marbles were there at first?

Have fun.
Best wishes

Hi Uncle Tianzhu,
There seems to be more than one possible correct answer for this question. I have posted a reply to \"livewith_vanilla\" to seek her clarification for this \"One quick(inaccurate) example is this:.....\"[/quote]there is more than one verytime i try i get a different answer

[tianzhu]

Hi VC


It’s nice to hear from you.

The question posed by livewith_vanilla is an interesting one. Unlike more familiar questions involving two changed quantities, the number (124) involved in the transaction is in one single lot.

Usually questions involving two changed quantities can be solved by Units and Parts, Model Drawing or equivalent ratios where numbers are presented in a tabulated list.

In this particular question, MD is out. If you try to use UP, you’ll also face obstacles. I also hit the dead end trying to get the answer. However, if you try to use equivalent ratios, you’ll be able to get the answer of 26 based on the context in the question.I am not sure if this is the actual question from any test papers or books or just an example given by livewith_vanilla.As such, there may be multiple answers.

Best wishes

[CoffeeCat]

Mr tianzhu, is your equivalent ratio method the one where you make two listings of multiples of 13 and 5 separately and pick the first 2 which has a difference of 124?


I agree that this question is too vague ( so multiple solutions existed). Perhaps a sentence should be added saying that only the lowest answer is required.
On the other hand, until livewithvanilla elaborate more, I will think that it is highly unlikely that such a question actually appeared as a homework question for p6. It is my guess that she is trying to illustrate a quick example of questions involving 2 changed quantities.
In any case I look forward to hearing from livewithvanilla the simple method=).

[tianzhu]

Hi Coffeecat


I guess you are a coffee lover.

Let’s hold our curiosity for a while and wait for livewith_vanilla to come back with the actual question next week.Her question is pretty unique as compared to the usual question concerning two changed quantities.

And yes, you are correct, just make a list.

Best wishes

[tianzhu]

Hi


While waiting for livewith_vanilla to come back with her question, I would like to put up two familiar types of questions concerning two changed quantities types of questions. Questions of this genre can be solved using Units and Parts, Model Drawing or Making a list (Equivalent ratio).

You may want to compare them with the question from livewith_vanilla to see the difference.

1)The ratio of Ryan’s pocket money to John’s pocket money was 3 : 2. After Ryan saved $15 and John spent $8, the ratio of Ryan’s pocket money to John’s pocket money was 3 : 1. How much money did Ryan have at first?

2) The number of Malvin’s stamps to Ken’s stamps was 2:3. After Malvin bought another 8 stamps and Ken lost 5 stamps, Malvin now has 4/5 as many stamps as Ken. Find the total number of stamps the two boys had at first.

Best wishes