Q&A - PSLE Math

[Jwoofamily]

Use model.


If jack give aqil 52 cards and they have same number means the model is like this.

J [ ][ 52 ][ 52 ]
A [ ]

If A gives 34 to J, the model will be as shown below whereby 34+34+52+52=4 units.

J [][][][34][34][ 52 ][ 52 ]
A [][][]

Find 1 unit and you can find solve the problem by tracing back to the original quantity.

[tianzhu]

happyheart:

Hi,

pls help with this question. Thanks!

Andy, Brad, Colin shared money to buya present for their teacher. The ratio of the amount of money contributed by Andy to the total amount contributed by Brad, Colin and Dominic was 1:5. Brad contributed 1/11as much as the total contributed by Dominic. If Andy contributed $2.10 more than Brad, how much did Dominic contribute?

Hi

One possible solution.

A:(: (B+C+D) ------- 1:5 -------3:15

B:D ------1:11

Hence , C ------3

2u ------ 2.1

1u ------ 1.05

D ------- 11*1.05 ------ 11.55

Best wishes

[Michaelia0816]

Tianzhu, can u help me with my sec 1 question, I will send u by PM, note: give me workings

Ty

[tianzhu]

Michaelia0816:

Tianzhu, can u help me with my sec 1 question, I will send u by PM, note: give me workings

Ty

Hi girl

I regret to say that I may not be able to be of any help.

I know next to nothing about the secondary maths as my kid is very much on his own. I’ve not been reading maths books for a few years already.

You may post your questions in the thread on “Secondary maths”.

I am sorry.

Happy New Year

Best wishes

[Michaelia0816]

tianzhu:

Michaelia0816:

Tianzhu, can u help me with my sec 1 question, I will send u by PM, note: give me workings

Ty

Hi girl

I regret to say that I may not be able to be of any help.

I know next to nothing about the secondary maths as my kid is very much on his own. I’ve not been reading maths books for a few years already.

You may post your questions in the thread on “Secondary maths”.

I am sorry.

Happy New Year

Best wishes

Never mind, Ty, happy Chinese New Year

[ozora]

speedmaths.com:

ozora:

I need some pointers in this question.

Zara had 70 more dresses than shirts. She sold 3/4 of the dresses and 3/5 of the shirts. She sold 126 more dresses than shirts. How many dresses were there in beginning?
Besides using models or algebra, any other alternative method like using units to get the answer 460.If possible can provide the solution

Hi ozora,

One Possible Solution:

Look at the 2 denominators; 4 and 5.
A common multiple of 4 and 5 is 20.

Let Zara have 20 boxes of shirts.
Let Zara have (20 boxes + 70) dresses.

She sold 3/4 of the dresses;
She sold (15 boxes + 52.5) dresses.

She sold 3/5 of the shirts;
She sold 12 boxes of shirts.

She sold 126 more dresses than shirts.

15 boxes + 52.5 → 12 boxes + 126
(Subtract 52.5 from both sides of the equation)
15 boxes + 0 → 12 boxes + 73.5
(Subtract 12 boxes from both sides of the equation)
3 boxes + 0 → 0 box + 73.5
3 boxes → 73.5
1 box → 24.5
20 boxes → 490
490 + 70 → 560 dresses (at first)

Hope this helps.

Cheers


speedmaths.com


.

Thanks.

[cimman]

happyheart:

Hi, one more please. I am always confused when there is transfer back and forth.Thanks.


Jack and Aqil had some game cards. If Jack gave Aqil 52 cards, he would have the same number of cards as Aqil. If Aqil gave Jack 34 cards, the ratio of the number of cards Aqil had to the number of cards Jack had would be 3:7.How many cards did Jack have at first?

actually, you should see this as a Double If question rather than a back and forth transfer question. Double If question is easy to recognize because there are 2 Ifs in the question. The key thing to note in Double If question is the starting point (Before) is the same in both If cases. Work your way up to the Before values in both cases (each If statement is a case) and equate them together.

[YumYum]

Hi, can anyone pls help with these qns:


1) there were 900 more chocolates than lollipops in a candy shop.
After the shop ordered more lollipops and sold some chocolates, the number of lollipops increased by 20% and the number of chocolates decreased by 30%.

Given that there were 370 more lollipops than chocolates in the end, find the total number of chocolates and lollipops in the shop at first.


2) Sonia has some money to buy some photo albums and photo frames.
If she buys 7 similar photo albums and 3 similar photo frames, she will be short of $27.10.

If she buys 2 similar photo albums and 5 similar photo frames, she will have $19 left.

If a photo frame costs $8.20, how much money does Sonia have?

Thanks 

[jieheng]

YumYum:

Hi, can anyone pls help with these qns:


1) there were 900 more chocolates than lollipops in a candy shop.
After the shop ordered more lollipops and sold some chocolates, the number of lollipops increased by 20% and the number of chocolates decreased by 30%.

Given that there were 370 more lollipops than chocolates in the end, find the total number of chocolates and lollipops in the shop at first.


Thanks 

1)

At first
C 10u + 900
L 10u

the number of chocolates decreased by 30% --> - (3u + 270)

the number of lollipops increased by 20% --> + 2u

C 10u + 900 - (3u + 270) --> 7u + 630

L 10u + 2u --> 12u

Given that there were 370 more lollipops than chocolates in the end

12u - (7u + 630) --> 370
5u --> 1000
1u --> 200

the total number of chocolates and lollipops in the shop at first

20u + 900 --> 20*200 + 900 = 4900 (Ans)

[jieheng]

YumYum:

Hi, can anyone pls help with these qns:



2) Sonia has some money to buy some photo albums and photo frames.
If she buys 7 similar photo albums and 3 similar photo frames, she will be short of $27.10.

If she buys 2 similar photo albums and 5 similar photo frames, she will have $19 left.

If a photo frame costs $8.20, how much money does Sonia have?

Thanks 

If she buys 7 similar photo albums and 3 similar photo frames, she will be short of $27.10

3 similar photo frames --> 3*8.2 = 24.6

If she buys 7 similar photo albums only , she will be short of $2.50
(27.1 - 24.6 = 2.5)

If she buys 2 similar photo albums and 5 similar photo frames, she will have $19 left.

5 similar photo frames --> 5*8.2 = 41

If she buys 2 similar photo albums only, she will have $60 left.
(19 + 41 = 60)

Price of one photo album = (2.5+60)/5 = 12.5

the money that Sonia has = 2*12.5 + 5*8.2 + 19 = 85 (Ans)