Q&A - PSLE Math

[alng]

speedmaths.com:

Hi,

You may use the Bags and Boxes Method to solve ALL the Double-Ratios problems for PSLE Maths:
(The Bags and Boxes Method can be found in the book: Raffles Maths Tricks - Volume 1; first printed in 2006.)

Thanks very much! I have come across this method before but never realise it is for Double Ratio problems. In fact, never encounter this term before. Thanks!

[Winx5015]

Hi,


Pse help me with the following questions!

(1). Kelly and Susan had some money each. If Kelly spent 4100 each day and Susan spent $50 each day, Kelly will still have $500 left when Susan had spent all her money. If Kelly spent $50 each day and Susan spent $100 each day, Kelly will still have $2300 left when Susan had spent all her money. How much did each of them have?

(2). Stefane and Lee Ling have some money. If Stefane gives Lee Ling $4.50, the two girls will have an equal amount of money. If Lee Ling gives $4.50 to Stefane, Stefane will have twice as much as Lee Ling. How much money do the 2 girls have altogether?

Thanks!

[kamom]

Given that one and only one of the following statements is correct, which one is correct?


1)All the statements below are correct
2)None of the statements below is correct
3)One of the statements above is correct
4)All of the statements above is correct
5)None of the statements above is correct

Ans is (5), can someone explain to me :idea:

THANKS A MIL

[Nebbermind]

Winx5015:

If Kelly spent 4100 each day and Susan spent $50 each day....,

do u mean $100?

[tianzhu]

Winx5015:

(1). Kelly and Susan had some money each. If Kelly spent 4100 each day and Susan spent $50 each day, Kelly will still have $500 left when Susan had spent all her money. If Kelly spent $50 each day and Susan spent $100 each day, Kelly will still have $2300 left when Susan had spent all her money. How much did each of them have?

Hi

Please study the solution for a similar question.It will help to solve your question.

For your question,

3 units ------- 1800 (2300-500)

1 unit ------ 600

Kelly ------- 2900

Susan ------1200

Best wishes

http://farm6.staticflickr.com/5142/5614468685_555807d62e_z.jpg\">

[Winx5015]

Hi Nebbermind,


U are right. should be $100 instead of 4100. Sorry, is a typo erro.

Thanks.

[tianzhu]

Winx5015:

(2). Stefane and Lee Ling have some money. If Stefane gives Lee Ling $4.50, the two girls will have an equal amount of money. If Lee Ling gives $4.50 to Stefane, Stefane will have twice as much as Lee Ling. How much money do the 2 girls have altogether?

Thanks!

Hi

Please study this solution for an earlier question.

Quite similar, it may help.

For your question, the transfers are in two directions.

1 unit ----- 4.5+4.5+4.5+4.5 ----- 18

S ----- 31.5
LL ----- 22.5
Total ----- 54

Best wishes.

http://farm2.staticflickr.com/1389/5112750348_b9f86799b4_z.jpg\">

[genevieve08]

(1) 100 - 50 = 50

2300/50 = 46
46x50 = 2300
k-->2300+2300 = 4600
4600-500=4100
4100/4100 = 0
50/0 = 50

Kelly have $4600 and Susan have $50


Scenario 1 Scenario 2 (2)
S : L S:L
1u+4.50:1u-4.50 2p-4.50:1p+4.50
3u+4.50 :3-4.50 4p-4.50:2p+4.50

4.5x4 = 18
18x2 =36 [because comparing two scenarios ]
36 + 4.5 = 40.5
40.5/4 = 10.125
10.125x2 = 20.25
20.25+4.5 = 24.75
24.75 + 36 = 60.75

they have $60.75 altogether.
:siam:

[Nebbermind]

genevieve08:

(1) 100 - 50 = 50

2300/50 = 46
46x50 = 2300
k-->2300+2300 = 4600
4600-500=4100
4100/4100 = 0
50/0 = 50

Kelly have $4600 and Susan have $50


Scenario 1 Scenario 2 (2)
S : L S:L
1u+4.50:1u-4.50 2p-4.50:1p+4.50
3u+4.50 :3-4.50 4p-4.50:2p+4.50

4.5x4 = 18
18x2 =36 [because comparing two scenarios ]
36 + 4.5 = 40.5
40.5/4 = 10.125
10.125x2 = 20.25
20.25+4.5 = 24.75
24.75 + 36 = 60.75

they have $60.75 altogether.
:siam:

Q1. If Susan had $50, she would not have been able to spend $100.

Q2. I think Tianzhu provided the correct solution above

[MathIzzzFun]

Winx5015:

Hi,


Pse help me with the following questions!

(1). Kelly and Susan had some money each. If Kelly spent $100 each day and Susan spent $50 each day, Kelly will still have $500 left when Susan had spent all her money. If Kelly spent $50 each day and Susan spent $100 each day, Kelly will still have $2300 left when Susan had spent all her money. How much did each of them have?


Thanks!

Hi

If Kelly spent $50 & Susan spent $100, Kelly will have $2300 left
Kelly's spending : Susan's spending --> 1u : 2u

Kelly's money --> 1u + $2300
Susan's money --> 2u

If Kelly spent $100 & Susan spent $50, Kelly will have $500 left
Kelly's spending : Susan's spending --> 4u : 2u
Kelly's money --> 4u + $500
Susan's money --> 2u

So, 4u + $500 = 1u + $2300
3u --> $ 1800
1u --> $ 600

4u + $ 500--> $2900
2u --> $ 1200
Kelly had $ 2900, Susan had $ 1200

cheers.