Q&A - PSLE Math

[tianzhu]

Hi


In this question, a student should note that the total number of boys and girls remains the same before and after the transfer.

We have two unknowns and two equations.

Students who are taught SE by their tutors or parents may use them.

For those without knowledge of SE, they may solve the equations pictorially or use letters of the alphabets as representation. Alternatively, they may also use units and parts as representation.

Best wishes

http://farm6.static.flickr.com/5263/5738959768_cab69b70e7_z.jpg\">

[chrisu]

Hi Tianzhu,


I'm dead clear with your pictorial! Thanks a lot. :boogie:

tianzhu:

Hi

In this question, a student should note that the total number of boys and girls remains the same before and after the transfer.

We have two unknowns and two equations.

Students who are taught SE by their tutors or parents may use them.

For those without knowledge of SE, they may solve the equations pictorially or use letters of the alphabets as representation. Alternatively, they may also use units and parts as representation.

Best wishes

http://farm6.static.flickr.com/5263/5738959768_cab69b70e7_z.jpg\">

[shurley197323]

Pls help. A container has a mass of 1 4/5kg when it is completely filled with sweets.It has a mass of 1 3/10kg when 3/8 of the sweets are removed. What is the mass of the container when it is empty ?

Many thanks.

[Belle2011]

shurley197323:

Pls help. A container has a mass of 1 4/5kg when it is completely filled with sweets.It has a mass of 1 3/10kg when 3/8 of the sweets are removed. What is the mass of the container when it is empty ?

Many thanks.

Do a subtraction ie 1 4/5 - 1 3/10 will give you the mass of 3/8 sweets.
From there, you can find the mass of 8/8 sweets.
Once found, you can subtract it from 1 4/5 to get the mass of container when it is empty.
Sorry, I dont have a calculator now, so can't work out the details.

Cheers,
Belle.

[shurley197323]

Thanks Belle 2011. But I don’t quite get it. Can someone advise me further?

[lizawa]

shurley197323:

Thanks Belle 2011. But I don't quite get it. Can someone advise me further?

This is the solution.
http://i52.tinypic.com/1z1r28m.jpg\">

[shurley197323]

Thanks.lizawa.

[MathIzzzFun]

match3frog:

MathIzzzFun:

[quote=\"match3frog\"]Please help with this question:


Jovi had 2 strings, string A and string B. Initially, string A was thrice the length of string B. Jovi then cut 9.1m from string A and 140cm from string B. The length of string B became 1.5 times of string A. What was the length of string A at first?

Thanks!

Hi match3frog

this was asked in another thread - http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=27&t=6373&start=3580

or find the solution at http://www.flickr.com/photos/62167097@N02/5709910478/in/photostream

cheers.

Thanks so much for your fast response and showing me the link! Much appreciated! :lovesite:[/quote]Hi match3frog

you are welcome :lol:

cheers.

[MathIzzzFun]

bobsg01:

Thanks MathIzzzFun.


:goodpost:

Hi bobsg01,

you are welcome :lol:

cheers.

[Neat]

tianzhu:

Neat:

What made you decide to multiply by 4 to get the equivalent ratio?

Hi

We are given that the total number of ducks and cows is between 20 and 40.

We are also given the ratio of the total number of ducks' legs to the total number of cows' legs is 5:9.

Given this ratio, a student is expected to find out the number of animals.

A cow has 4 legs and a duck has 2 legs.

Hence, the number showing the number of cow’s legs has to be a multiple of 4.Likewise the number showing the number of duck’s legs has to be a multiple of 2.

That’s why we multiply the given ratios 5:9 by 4 to get 20:36.

This gives us 10:9 as the ratio for the number of ducks to the number of cows. This is not within the range of 20 and 40.

Multiply by 2 to get an equivalent ratio of 20:18 which is 38 and within the range.

Best wishes

[quote]Thanks tianzhu for your detailed and clear explanation.

Thanks again.
:salute: [/quote]