Q&A - PSLE Math

[MathIzzzFun]

fxchow:

MathIzzzFun:

[quote=\"fxchow\"]Hi,


Please help on this P6 math. TIA
If David after giving 1/3 of his money to Ken, Ken will have $70 more than David.
If David after giving 1/5 of his money to Ken, Ken will have $10 money than David. How much does David have initially?

At first, David --> 15 units (LCM of 3 & 5)

IF David give 1/3 (=5 units) to Ken,
David --> 10 units
Ken --> 10 units + $70
Ken, at first --> 5 units + $70

If David give 1/5 (=3 units) to Ken,

David --> 12 units
Ken --> 8 units + $70

Ken will have $10 more than David

so, 8 units + $70 = 12 units + $10
1 unit --> $15

At first, David --> 15 x $15 = $225

cheers.

Hi MathIzzzFun,

Thanks for you reply.

I still can't figure out the below statement.

8 units + $70 = 12 units + $10

Why 12 units + $10? and why both side is equal?

Sorry for so many questions.[/quote]
http://i50.tinypic.com/2hyuz9w.png\">

cheers.

[fxchow]

Hi MathIzzzFun,


I got it now. Thank you for your clear picture.

[Mary Joy]

Hi…I have a doubt in an Angle sum but can’t understand if i just write here without a picture. Anybody pls. highlight any chance i can attach an image here.? If so pls. explain how to attach an image so that draw the angle & post here.Thanks.

[MathIzzzFun]

Mary Joy:

Hi..I have a doubt in an Angle sum but can't understand if i just write here without a picture. Anybody pls. highlight any chance i can attach an image here.? If so pls. explain how to attach an image so that draw the angle & post here.Thanks.

Click on \"Post Reply\" at the end of the last post to go into the edit/post mode.

scroll down the screen and you will see the \"tinypic\" plugin.. attach your picture file (in image format - jpg, png, bmp), resize image size to \"message board\" -- click upload and then add to post.

cheers.

[Mary Joy]

MathIzzzFun:

Mary Joy:

Hi..I have a doubt in an Angle sum but can't understand if i just write here without a picture. Anybody pls. highlight any chance i can attach an image here.? If so pls. explain how to attach an image so that draw the angle & post here.Thanks.

Click on \"Post Reply\" at the end of the last post to go into the edit/post mode.

scroll down the screen and you will see the \"tinypic\" plugin.. attach your picture file (in image format - jpg, png, bmp), resize image size to \"message board\" -- click upload and then add to post.

cheers.

Hi Mathizzfun...Thanks for the feedback.

[Mary Joy]

Hi…Pls. help me to find out the answer.


The figure below is not drawn to scale.CDEF is a trapezium and AB=BC.
<EFC is twice of <FCA. BCD is a right angled triangle.

a) Find <FCD
b) Find <DBA

[MathIzzzFun]

Mary Joy:

http://i47.tinypic.com/2n8xah4.jpg\"> Hi..Pls. help me to find out the answer.


The figure below is not drawn to scale.CDEF is a trapezium and AB=BC.
<EFC is twice of <FCA. BCD is a right angled triangle.

a) Find <FCD
b) Find <DBA

This was discussed on pg 862 ... http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280&start=8610

cheers.

[Mary Joy]

quote=\"SAHMwith2boys\"]Can someone help with the below question:

http://i46.tinypic.com/14qyd3.jpg\">

It's taken from 2012 CHIJ CA1 paper.[/quote]


http://i48.tinypic.com/hvqj42.png\">

cheers.[/quote]

This method seems a bit tough for Primary level, was wondering is there any other way to do this? [/quote]

The solution is not beyond P6 students.

2 key information are provided - triangle ABC is isosceles and angle AGE = 75 deg. So, one has to made use of these to work out the solution.

another approach is to work out the angle CAG in terms of the angles EFC and FCA and then use the interior angles of quadrilateral ACFG to work out angle FCA (1u)

angle CAG = 180 -(90-1u) = 1u + 90
in quadrilateral ACFG
angle EFC + angle FCA + angle CAG + angle AGE = 360
2u + 1u + 1u + 90 + 75 = 360
4u = 195, 1u = 48.75

http://i45.tinypic.com/qstohc.png\">

cheers.[/quote]
Hi..,

Thanks for the answer. Actually this is from CHIJ question paper and the answer given is 6 degree. But your's is 7.5 degree.

[Mary Joy]

quote=\"SAHMwith2boys\"]Can someone help with the below question:

http://i46.tinypic.com/14qyd3.jpg\">

It's taken from 2012 CHIJ CA1 paper.[/quote]


http://i48.tinypic.com/hvqj42.png\">

cheers.[/quote]

This method seems a bit tough for Primary level, was wondering is there any other way to do this? [/quote]

The solution is not beyond P6 students.

2 key information are provided - triangle ABC is isosceles and angle AGE = 75 deg. So, one has to made use of these to work out the solution.

another approach is to work out the angle CAG in terms of the angles EFC and FCA and then use the interior angles of quadrilateral ACFG to work out angle FCA (1u)

angle CAG = 180 -(90-1u) = 1u + 90
in quadrilateral ACFG
angle EFC + angle FCA + angle CAG + angle AGE = 360
2u + 1u + 1u + 90 + 75 = 360
4u = 195, 1u = 48.75

http://i45.tinypic.com/qstohc.png\">

cheers.[/quote]
Hi..,

Thanks for the answer. Actually this is from CHIJ question paper and the answer given is 6 degree. But your's is 7.5 degree.

[MathIzzzFun]

Mary Joy:

quote=\"SAHMwith2boys\"]Can someone help with the below question:

http://i46.tinypic.com/14qyd3.jpg\">

It's taken from 2012 CHIJ CA1 paper.

http://i48.tinypic.com/hvqj42.png\">

cheers.[/quote]

This method seems a bit tough for Primary level, was wondering is there any other way to do this? [/quote]

The solution is not beyond P6 students.

2 key information are provided - triangle ABC is isosceles and angle AGE = 75 deg. So, one has to made use of these to work out the solution.

another approach is to work out the angle CAG in terms of the angles EFC and FCA and then use the interior angles of quadrilateral ACFG to work out angle FCA (1u)

angle CAG = 180 -(90-1u) = 1u + 90
in quadrilateral ACFG
angle EFC + angle FCA + angle CAG + angle AGE = 360
2u + 1u + 1u + 90 + 75 = 360
4u = 195, 1u = 48.75

http://i45.tinypic.com/qstohc.png\">

cheers.[/quote]
Hi..,

Thanks for the answer. Actually this is from CHIJ question paper and the answer given is 6 degree. But your's is 7.5 degree.[/quote]

use the given answer and work backwards to see whether it is correct.

The answer key is not always correct

cheers