Q&A - PSLE Math

[ozora]

MathIzzzFun:

ozora:

Need help: father ->when I was your age you were 3 years old.

Son-> when I become your age you will be 63 years old. How old is the father And son respectiveLy now?

http://i46.tinypic.com/1ekkmw.png\">


cheers

Thanks maths

[mama_10]

Hi,


Need help in this question.
Class A and Class B have the same number of pupils. The ratio of the number of boys in Class A to the number of boys in Class B is 3:2. The ratio of the number of girls in Class A to the number of girks in Class B is 3:5. Find the ratio of the number of boys to the number of girls in Class A.

Thank you!

[MathIzzzFun]

mama_10:

Hi,


Need help in this question.
Class A and Class B have the same number of pupils. The ratio of the number of boys in Class A to the number of boys in Class B is 3:2. The ratio of the number of girls in Class A to the number of girks in Class B is 3:5. Find the ratio of the number of boys to the number of girls in Class A.

Thank you!

Since the Class A and Class B have same number of pupils, the difference between number of boys in A and B, and the difference between the number of girls in A and B, must be the same.

Boys --> Class A : Class B = 3 : 2 = 6 : 4
Girls --> Class A : Class B = 3 : 5
ratio of number of boys to number of girls in A = 6 : 3 = 2 : 1


http://i45.tinypic.com/15gc6qs.png\">

cheers.

[mama_10]

MathIzzzFun:

mama_10:

Hi,


Need help in this question.
Class A and Class B have the same number of pupils. The ratio of the number of boys in Class A to the number of boys in Class B is 3:2. The ratio of the number of girls in Class A to the number of girks in Class B is 3:5. Find the ratio of the number of boys to the number of girls in Class A.

Thank you!

Since the Class A and Class B have same number of pupils, the difference between number of boys in A and B, and the difference between the number of girls in A and B, must be the same.

Boys --> Class A : Class B = 3 : 2 = 6 : 4
Girls --> Class A : Class B = 3 : 5
ratio of number of boys to number of girls in A = 6 : 3 = 2 : 1


http://i45.tinypic.com/15gc6qs.png\">

cheers.

Sorry, I dont understand why change the Boys ratio from 3:2 to 6:4?
thank you

[kwcllf]

mama_10:

MathIzzzFun:

[quote=\"mama_10\"]Hi,


Need help in this question.
Class A and Class B have the same number of pupils. The ratio of the number of boys in Class A to the number of boys in Class B is 3:2. The ratio of the number of girls in Class A to the number of girks in Class B is 3:5. Find the ratio of the number of boys to the number of girls in Class A.

Thank you!

Since the Class A and Class B have same number of pupils, the difference between number of boys in A and B, and the difference between the number of girls in A and B, must be the same.

Boys --> Class A : Class B = 3 : 2 = 6 : 4
Girls --> Class A : Class B = 3 : 5
ratio of number of boys to number of girls in A = 6 : 3 = 2 : 1


http://i45.tinypic.com/15gc6qs.png\">

cheers.

Sorry, I dont understand why change the Boys ratio from 3:2 to 6:4?
thank you[/quote]
Boys --> Class A : Class B = 3 : 2 = 6 : 4
Girls --> Class A : Class B = 3 : 5

Since the number of pupils in Class A and Class B are the same,
when you change the ratio from 3 : 2 to 6 : 4,
The ratio of the total number of Boys + Girls in Class A = 6+3 = 9

The ratio of the total number of Boys + Girls in Class B = 4+5 = 9

When they are equal, then you can compare.

[libran269]

can we use equations/algebra to solve?

Is this have to be solved using the above method?
I am familirising the methods used for maths.
Thanks

[MathIzzzFun]

mama_10:

MathIzzzFun:

Hi,


Need help in this question.
Class A and Class B have the same number of pupils. The ratio of the number of boys in Class A to the number of boys in Class B is 3:2. The ratio of the number of girls in Class A to the number of girks in Class B is 3:5. Find the ratio of the number of boys to the number of girls in Class A.

Thank you!

Since the Class A and Class B have same number of pupils, the difference between number of boys in A and B, and the difference between the number of girls in A and B, must be the same.

Boys --> Class A : Class B = 3 : 2 = 6 : 4
Girls --> Class A : Class B = 3 : 5
ratio of number of boys to number of girls in A = 6 : 3 = 2 : 1


http://i45.tinypic.com/15gc6qs.png\">

cheers.

Sorry, I dont understand why change the Boys ratio from 3:2 to 6:4?
thank you

.. hope this explains...

http://i46.tinypic.com/120schf.png\">

cheers.

[Lazy snake]

:heresmyfish: Hi,I'm new here. :rahrah:

[Easy-going]

Hi

Desperately need help in solving this sum for my son.
Putri and David each have some money. If Putri spends $20, the ratio of the amount of money Putri has to the amount of money David has will become 3:7. If David spends $20, the ratio will become 8:12. How much money does each boy have?

[Jwoofamily]

Using units and parts method.


putri : 8 parts - 20 = 3U which means 24 parts = 9U + 60
David : 7U - 20 = 12 parts which means 24 parts = 14U - 40

Therefore, 9U + 60 = 14U - 40
Answer is U = 20

That means, Putri has 3U which means $60 after spending $20. That means Putri should have $80. David has 7U which means $140.