Q&A - PSLE Math

[Dharma]

Muffins:

WOW, Dharma, would have NEVER thought of that solution!

Hi Muffins,

Glad u like it.

[James Ang]

a few questions for discussion, not too difficult


1)A bag contains some yellow and green balls. If we remove 1 yellow ball, the ratio of the number of the remaining yellow balls to the number of green balls is 1:6.If we remove 2 green balls instead of 1 yellow ball, the ratio of the number of yellow balls to the number of green balls is 1:4.How many balls are there in the bag at first?

2)Jim and Ron are to sell some donation tickets.If Jim sells 80 tickets a day and Ron sells 64 tickets a day, Jim will have 12 tickets left when Ron has sold all his tickets. If Jim sells 60 tickets a day and Ron sells 72 tickets a day, Jim will have 312 tickets left when Ron has sold all his tickets.How much more will Jim collect than Ron when both have sold all their tickets at $24 per ticket?

3)Kim bought game cards at $4 each and sold at $9 each. Each customer either bought 1 or 2 game cards.180 customers bought 2 game cards.For every 2 game cards bought,1 game card was given away free.Kim earned $1340. How many customers bought 1 game card?

[xxjustakidxx]

lizawa:

These 2 questions constitute 5 marks each (out of 100 marks). There are about 4 - 5 such questions. And others are 4 and 3 mark. Total for this section is 50 marks, ie. 50%.


You are right, some questions are not solvable by algebra, model may be easier !

Personally, I feel that algebra is easier, as after the PSLE exam, I sat down, find the questions on the internet and tried to use algebra to solve then (I learned it only after the exam) and bingo, I got all of them.

[VitoRelax]

For the angle question, can explain again how to derive that AD=AC=AB ?


Did the question said that it is the radii of an arc ?

Thanks

[VitoRelax]

VitoRelax:

For the angle question, can explain again how to derive that AD=AC=AB ?


Did the question said that it is the radii of an arc ?

Thanks

Anyone ?

[cafelatte]

Is it confirmed during PSLE not allowed to bring in model ruler ?


This is the model ruler used in my child's school :
http://i781.photobucket.com/albums/yy96/cafelatte22/mruler.jpg\">

[angela]

Hi, can anyone help me on these 4 questions:


1) There were some $2, $5 and $100 notes in Jane’s wallet. The value of the $2, $5 and $100 was in the ratio 4 : 5 : 3. After spending 50% of her $100 notes, 100 of her $2 notes and 4/5 of her $5 notes. Jane had $450 left. FInd the total amount of money Jane had in her wallet at first?

2) Ace Drama Company sold some tickets for a children’s performance. It sold the same number of $8 and $5 tickets in week 1 and collected a total of $1664. In week 2, it sold 96 $8 and $5 tickets. If the company collected $632 more from the sale of $8 tickets than teh $5 tickets in the two weeks, how many $8 tickets were sold altogether?

3) Adam and Rahmad shared some beads. If Adam gave 1/3 of his share to Rahmad, Rahmad would have 70 more than Adam. If Adam gave 1/5 of his share to Rahmad, Rahmad would have 10 more than Adam. How many beads does Adam have at first?

4) Miss Tang bought 750 apples and pears. The fruits were mixed up and placed in two baskets, X and Y. There were twice as many fruits in Y as in X. The ratio of the number of apples in basket X to the number of pears in Y was 3 : 4. The ratio of the number of pears in X to the number of apples in Y was 1 : 3.
(a) What is teh ratio of the total number of pears to the total number of fruits?
(b) How many apples did Miss Tang buy altogether?

Thanks

[Vanilla Cake]

angela:

1) There were some $2, $5 and $100 notes in Jane's wallet. The value of the $2, $5 and $100 was in the ratio 4 : 5 : 3. After spending 50% of her $100 notes, 100 of her $2 notes and 4/5 of her $5 notes. Jane had $450 left. Find the total amount of money Jane had in her wallet at first?

Value

$2 : $5 : $100
4 : 5 : 3

1/2 x 3 = 1.5 units (for $100 notes)
1/5 x 5 = 1 unit (for $5 notes)

1.5u + 1u + 4u-200 = 450 (200 from 100 of her $2 notes spent)
6.5u = 650
u = 100

12u = $1200 (12u from 4u+5u+3u)
At first, Jane had $1200 in her wallet.

angela:

2) Ace Drama Company sold some tickets for a children's performance. It sold the same number of $8 and $5 tickets in week 1 and collected a total of $1664. In week 2, it sold 96 $8 and $5 tickets. If the company collected $632 more from the sale of $8 tickets than the $5 tickets in the two weeks, how many $8 tickets were sold altogether?

Week 1
$5 tickets -> 1664/(8+5) = 128
$8 tickets -> 128 (Given info that the same number of $8 and $5 tickets was sold in week 1)

Value
$5 tickets -> $(128x5) = $640
$8 tickets -> $(128x8) = $1024

Difference -> $(1024-640) = $384

Week 2
Difference -> $(632-384) = $ 248

In week 2, it sold 96 $8 and $5 tickets, so (96x8)-248 = $520
Number of $5 tickets sold was 520/(8+5) = 40
Number of $8 tickets sold was 96-40 = 56

Altogether, the number of $8 tickets sold in week 1 and week 2 was 56+128 = 184

angela:

3) Adam and Rahmad shared some beads. If Adam gave 1/3 of his share to Rahmad, Rahmad would have 70 more than Adam. If Adam gave 1/5 of his share to Rahmad, Rahmad would have 10 more than Adam. How many beads does Adam have at first?

A - Adam
R - Rahmad

2/3A + 70 = R + 1/3A
1/3A + 70 = R

4/5A+10 = R + 1/5A
3/5A + 10 = R

1/3A + 70 = 3/5A + 10
4/15A = 60
A = 15/4 x 60 = 15 x 15 = 225

At first, Adam had 225 beads

Pls refer to alternative methods posted by others for this question.
Refer http://www.onsponge.com/images/fbfiles/images/forum_2010_02_04_gap_difference_a.jpg, http://www.onsponge.com/images/fbfiles/images/forum_2010_02_04_sim_equations_a.jpg and http://farm3.static.flickr.com/2706/4331536564_d0ab20fb80_o.jpg.

angela:

4) Miss Tang bought 750 apples and pears. The fruits were mixed up and placed in two baskets, X and Y. There were twice as many fruits in Y as in X. The ratio of the number of apples in basket X to the number of pears in Y was 3 : 4. The ratio of the number of pears in X to the number of apples in Y was 1 : 3.
(a) What is the ratio of the total number of pears to the total number of fruits?
(b) How many apples did Miss Tang buy altogether?

A stands for apples
P stands for pears

A(X) : P(Y)
3 : 4

P(X) : A(Y)
1 : 3
2 : 6

750/3 = 250 (X)
250x2 = 500 (Y)

10u = 500
u = 50
6u = 300
15u = 750

300 : 750
2 : 5

(a) Ratio of the total number of pears to the total number of fruits is 2 : 5

(b) Since u = 50, 9u = 450
Number of apple that Mrs Tang bought altogether was 450

Check
Basket X
Apples : 150
Pears : 100

Basket Y
Apples : 300
Pears : 200

[Muffins]

Vanilla Cake:

...Basket Y

Apples : 300
Pears : 200

Hi Vanilla Cake, are you a secondary student?

[tianzhu]

Muffins:

Hi Vanilla Cake, are you a secondary student?

Aiyo, little Muffins, this is maths meh? It’s more like getting to know more about you.

Maybe, we will see some kiasu kids get connected and begin their love journey in KSP.

Just joking, but there is always a possibility.

Best wishes