MathIzzzFun:

sokk:

Hi,

Need help in these two questions.


2) Mrs Kee baked a total of 250 cookies for the pupils in her class. There were more boys thn girls in the class. She gave each boy a number of cookies equal to the number of boys in the class and each girl a number of cookies equal to the number of girls in the class. There were 22 pupils in the class.
a) How many girls were there in the class?
b) How many cookies did the boys receive altogether ?


Thanks!

using area model ...

http://i40.tinypic.com/znk48m.png\">

cheers.

I see.....very interesting .
:thankyou: MathIzzzFun !!

XXXX:

sokk:

Hi,

Need help in these two questions.

1) Mr Goh had 840 erasers and rulers in his shop. He sold 50% of the erasers and 75% of the rulers. He was left with 240 erasers and rulers. How many erasers did he have at first?

840, obviously!

What do u mean by \"840, obviously! \".............?

and to add on, I do think u sounded rude and arrogant.
I know quadratic equations and I'm sure a lot of parents here know it too but not to a p5 kiddo. That's y I'm here in this forum to seek for a solution on how to guide my p5.

speedmaths.com:

sokk:

Hi,

Need help in these two questions.

1) Mr Goh had 840 erasers and rulers in his shop. He sold 50% of the erasers and 75% of the rulers. He was left with 240 erasers and rulers. How many erasers did he have at first?

Thanks!

Hi sokk,

One possible solution, using the \"Advanced Model Method\" or \"Bags and Boxes Method\"\"

Mr Goh had 840 erasers and rulers in his shop.
Let Mr Goh put the erasers in 2 Bags, and the rulers in 4 Boxes

2 Bags + 4 Boxes → 840......................(Row 1)

He sold 50% of the erasers and 75% of the rulers
He sold 1 Bag of erasers and 3 Boxes of rulers

He is left with 1 Bag of erasers and 1 Box of rulers
He was left with 240 erasers and rulers

1 Bag + 1 Box → 240........................(Row 2)
(x 4)
4 Bags + 4 Boxes → 960.....................(Row 3)

(Row 3) - (Row 1)
2 Bags → 960 - 840 = 120 (erasers at first)

Hope this helps

Cheers

speedmaths.com


PS
Parents who wish to find out more about the \"Advanced Model Method\" may wish to browse through the book \"PSLE Maths - Advanced Model Method\", available at any Popular Book store.

.

Hi speedmaths,
Once again, thanks for your help . Shall go Popular and look for the book.

Cheers!

Hi,

Need help in these two questions.

1) Mr Goh had 840 erasers and rulers in his shop. He sold 50% of the erasers and 75% of the rulers. He was left with 240 erasers and rulers. How many erasers did he have at first?

2) Mrs Kee baked a total of 250 cookies for the pupils in her class. There were more boys thn girls in the class. She gave each boy a number of cookies equal to the number of boys in the class and each girl a number of cookies equal to the number of girls in the class. There were 22 pupils in the class.
a) How many girls were there in the class?
b) How many cookies did the boys receive altogether ?


Thanks!

[/quote]


Hope this helps..

http://i42.tinypic.com/nxuc79.png\">

cheers.[/quote]


Yes! The model really helps a lot. :thankyou: Really appreciate it.


Cheers

MathIzzzFun:

sokk:

Hi, I need help in these two questions. Pleae help. Thanks!


2) Shufen bought some strawberries from the supermarket.
After using 4/7 of it to make a strawberry cake, she bought another 36 strawberries and baked another cake exactly like the first.
3/7 of the remaining strawberries were used to make jam.
16 strawberries were left.
(a) How many strawberries were used to make jam?
(b) How many strawberries did she have at first ?

Q2 discussed @pg 301 - http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=68&t=25129&start=3000

cheers.

Hi,
Thanks for the help. Understood the solution for qtn 1, thanks!
But am still a bit lost for qtn 2. Why is 3/7 used=4/7left?

Thanks for helping .

Hi, I need help in these two questions. Pleae help. Thanks!


1) Mr Ong had 280 more files than notebooks in his bookstore.
After selling 3/4 of the files and 2/5 of the notebooks,
172 files and notebooks were left.
How many files did he sell?



2) Shufen bought some strawberries from the supermarket.
After using 4/7 of it to make a strawberry cake, she bought another 36 strawberries and baked another cake exactly like the first.
3/7 of the remaining strawberries were used to make jam.
16 strawberries were left.
(a) How many strawberries were used to make jam?
(b) How many strawberries did she have at first ?

tianzhu:

sokk:

Hi tianzhu,

So sorry for the mistake, it's $121.

Hi sokk

Yes, with 121, you can have a nice number as an answer.

You may present your answer in MD or Units format. Due to time constraints, I’ll do it in the Units way.

A comb costs 3/10 as much as 2 mirrors.

Comb ---- 3 units

Mirror ----- 5 units

6 mirrors and 7 combs cost $51.

6*5 units + 7*3 units ----- $51

51 units ----- $51

1 unit ----- $1

1 comb ----- $3

1 mirror ----- $5

Mrs Chew bought twice as many combs as mirrors for $121.

Consider a set or group of 2 combs and 1 mirror.

2*3 + 1*5 ---- $11

Number of groups ----- 121/11 ----- 11

Hence, number of combs bought by Mrs Chew ------ 2*11 ----- 22

Best wishes

Hi,
Thanks so much for the solution!

Cheers!

tianzhu:

sokk:

1) 6 mirrors and 7 combs cost $51. A comb costs 3/10 as much as 2 mirrors. Mrs Chew bought twice as many combs as mirrors for $124. How many combs did she buy?

Hi sokk

Please help to confirm if it is $121.

Best wishes

Hi tianzhu,

So sorry for the mistake, it's $121.

MathIzzzFun:

alternate approach using model/units:

http://i39.tinypic.com/f5aef8.jpg\">

cheers.

Hi MathIzzzFun,

Thanks for your model to this question, I understand it now.

Cheers !