Q&A - PSLE Math

[Emelyn]

Dharma:

Emelyn:

Hi,


I have a question :

In a soccer stadium, the number of female to male spectators is 3:7. After 287 female and 287 male left the stadium, the ratio of female to male spectators became 2:5. How many spectators were there at first ?

Can someone help me solve ?

Female : 3u – 287 = 2p
Male : 7u – 287 = 5p

15u – 1435 = 10p
14u – 574 = 10p

15u – 1435 = 14u – 574
1u = 861

No. of spectators in the stadium at first = 10u = 861 x 10 = 8610

Ok.... so, use algebra.
But can use algebra ? sorry if my question sounds so ignorant....

[corneyAmber]

Emelyn:

Ok.... so, use algebra.

But can use algebra ? sorry if my question sounds so ignorant....

PSLE is legitimate to use Algebra method. For that matter, as long as it is a valid method to derive the answer, it is acceptable. This should be the way, otherwise how to get 'think-out-of-the-box' answers if they exist?

[Emelyn]

ksi:

Emelyn:

Ok.... so, use algebra.

But can use algebra ? sorry if my question sounds so ignorant....

PSLE is legitimate to use Algebra method. For that matter, as long as it is a valid method to derive the answer, it is acceptable. This should be the way, otherwise how to get 'think-out-of-the-box' answers if they exist?

Ok. Noted. Thanks......

[corneyAmber]

Dharma:

ChiefKiasu:

[quote=\"James Ang\"]an interesting thinking question to share here.


Mainah had some money at first.she spent it all in 3 stores.In each store, she spent $2 more than half of what she had when she entered.
(a) How much did she spend at the last store?
(b)how much did she have at first?

(a) Amount spent in last store = S = S/2 + 2
=> Half of S = $2
=> S = $4

(b) Money Mainah had when entering 2nd store = $4 + $4 + $2 = $10
Money Mainah had when entering 1st store = $10 + $10 + $2 = $22

So Mainah had $22 at first.

http://www.postimage.org/image.php?v=PqrmctA[/quote]Ah...this is so like the bananas question that chamonix set for me in another thread... Quite common for P6 level huh?

[Emelyn]

tianzhu:

Hi


Another alternative is to use the Units Method.


Best wishes

Thanks Tianzhu, trytry and Vanilla Cake for all the explanation. I understand better now. .....

I was initially puzzled why the answer key wrote 3x3 = 9, and 7x3=21. Now I understand.

[tianzhu]

Emelyn:

tianzhu:

Hi


Another alternative is to use the Units Method.


Best wishes

Thanks Tianzhu, trytry and Vanilla Cake for all the explanation. I understand better now. .....

I was initially puzzled why the answer key wrote 3x3 = 9, and 7x3=21. Now I understand.

Hi

It always good to be able to identify the concepts correct before answering the question.This will lead to a more efficient method of problem solving.

As demonstrated in your earlier question, the Units Methods is a more efficient method.However, Units and Parts, is a very useful tool which is applicable to many types of questions, especially two changed quantities of different values.

Best wishes

[ruyu]

can you guys teach me a few algebra concepts that might help in PSLE. Thanks in advance! :thankyou:

[Maths Monster]

delete

[ruyu]

How to do this question? Please refer to the picture

http://www.postimage.org/image.php?v=aVnK1QS

[Vanilla Cake]

ruyu:

How to do this question? Please refer to the picture

http://www.postimage.org/image.php?v=aVnK1QS

Refer to http://www.kiasuparents.com/kiasu/forum/viewtopic.php?p=178599#178599 in Mathsguru's thread.