Q&A - P5 Math

[highanxiety]

Hi Udon

You might want to take note that they make used of constant total concept in before and after situation to solve, using LCM of 12, 4 and 3 is 12.

[Udon]

php:

Udon:

Thanks for the reply, but i do not understand how to calculate


Kenny....1 unit become 4 units
Sally......2 units become 8 units

------------------------------------------------------------------------------------------
How many pens must Kenny give back to Sarah so that she will have twice as many pens as him?

Kenny ------ 1 unit ------- 4 units
Sarah ------ 2 units ------- 8 units

9 - 4 ------ 5





72*5 ------- 360.

From the first part of the working, the total number of units they have is 12 units....Kenny (9 units) and Sarah (3 units)

For Sarah to have twice as many pens as Kenny, it means Kenny will have 1 unit and Sarah will have 2 units, giving total of 3 units...

In order solve the problem, you will have to equate both equations to have the same number of total units...i.e. 12 units...

So you will have to multiply x 4 for the second equation to get a total of 12 units....

Kenny - 1 unit x 4 = 4 units
Sarah - 2 units x 4 = 8 units

For Kenny,
Before - 9 units
After - 4 units

The difference of 5 units is given to Sarah....
5 units x 72 = 360

Hope my explanation helps...

Thanks...Thanks.

[Udon]

tianzhu:

Udon:

Thanks for the reply, but i do not understand how to calculate

Kenny....1 unit become 4 units
Sally......2 units become 8 units

Hi

Good Morning.

P5 students should be comfortable with changing from decimals to fractions and ratios.

1.4 ------ 14/10 ------- 7/5

A student should note that the total number of units stays the same in the various scenarios. Perhaps a good way is understand is to imagine Kenny and Sarah inside a box. The exchanges between them take place inside the box. Nothing flows out of the box, hence the total number of pens they had stays the same.

I’ve attempted to show the flow of events in this slide, as you can see nothing more than equivalent ratios is required to solve this question.

Hope this helps.

Best wishes

http://farm8.staticflickr.com/7232/7218581850_f5c8b8288e_z.jpg\">

Thankz for the clear illustration, I & my girl can understand better now. :))

[Udon]

highanxiety:

Hi Udon

You might want to take note that they make used of constant total concept in before and after situation to solve, using LCM of 12, 4 and 3 is 12.

Hi..Hi

Thanks for highlighting the concept....

[TulipisPink]

Thank you very much to all who has help in showing the lights in maths question.


You are the best !

Thanks again.

[MathIzzzFun]

NewMum2012:

http://i49.tinypic.com/b3wlqf.jpg\"> Hi Can anyone please help with this Question?

Hi

area of triangle PRV + area of triangle QSV
= 1/2 area of rectangle PQRS
= unshaded area + area of quadrilateral TUVW
I think you can complete the solution from here

cheers.

[CoffeeCat]

NewMum2012:

You quoted \"area of triangle PRV + area of triangle QSV

= 1/2 area of rectangle PQRS\"

Can you please explain how this is possible?

Thanks for your prompt response!

area of PRV = 1/2 * PS* PV
area of QSV = 1/2 * PS* VQ
area of PRV + QSV = 1/2 * PS * (PV+VQ) = 1/2 * PS *PQ

This looks like a maths olympiad question...

[MathIzzzFun]

NewMum2012:

You quoted \"area of triangle PRV + area of triangle QSV

= 1/2 area of rectangle PQRS\"

Can you please explain how this is possible?

Thanks for your prompt response!

Hi
Area of triangle PVR =area of triangle PVS (same base PV & same height PS=QR)
Area of triangle PVS + area of triangle QVS= 1/2 area of rectangle PQRS
so, area of triangle PVR + area of triangle QVS = 1/2 area of rectangle PQRS

cheers.

[cimman]

this question has been answered before:

http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=71&t=6373&start=740

quite some time ago, that is.

[cimman]

this question was answered before:

http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=71&t=6373&start=740

you should try the other question (the double square question) as well. it's also an interesting question.