Q&A - PSLE Math

[JadeDry]

Dharma:

JadeDry:

[quote=\"Dharma\"]
L(5u) + C(2u) = 300 ---------- (1)
L(2u) + C(5u) = 400 ---------- (2)

7L(1u) + 7C(1u) = 700 --------(1) + (2) = (3)
L(1u) + C(1u) = 100 ------- (3) divide by 7 = (4)

L(2u) + C(2u) = 200 -----------(5) = (4) x 2

L(3u) = 100 -------------- (1) – (5)
3u = 100/5
1u = 100/15

1u(L +C ) = 100
L + C = 100/(100/15) = 15
C = 15 – 5 = 10
Ratio => 10 : 5 = 2 : 1

Thank you Dharma, this helps a lot.

But one small question if I may-What does \"u\" stand for?

Oh I see...Thank you.

Units - represents the cost of shoes
1 pair of Leather shoes costs 5u
1 pair of Canvas shoes costs 2u[/quote]

[tianzhu]

noob:

Hi Dharma and tianzhu, need your help to solve following question:-


Alice, Betty and Cecilia shared the cost of a present. Alice paid 1/3 of the total amount of money paid by Betty and Cecilia. Betty paid 1/8 of the amount of money paid by Alice and Cecilia. Alice paid $60 less than Cecilia.
(a) How much did Betty pay?
(b) What was the cost of the present?

Hi

I believe this is a P5/P6 question and you may use the Units Method to solve such question.

The key to unlock this question is to recognise that the cost of the present is fixed.This means that the total number of units remains the same.

Alice:(Betty+Cecilia) ------ 1:3 -------9:27
Betty:(Alice+Cecila) ------1:8 ------- 4:32

Alice ----- 9 units
Betty ----- 4 units
Cecilia ----- 23 units

23 – 9 ---- 14
14 units ---- 60

Here we end up with 1 unit equals to $4.28.

This means we would be getting answers in decimals form.

Before I go on further,I would like you to check from the source what are the given answers.Also you may wish to confirm if the numbers in your question are in order.

Best wishes

[noob]

tianzhu:

noob:

Hi Dharma and tianzhu, need your help to solve following question:-


Alice, Betty and Cecilia shared the cost of a present. Alice paid 1/3 of the total amount of money paid by Betty and Cecilia. Betty paid 1/8 of the amount of money paid by Alice and Cecilia. Alice paid $60 less than Cecilia.
(a) How much did Betty pay?
(b) What was the cost of the present?

Hi

I believe this is a P5/P6 question and you may use the Units Method to solve such question.

The key to unlock this question is to recognise that the cost of the present is fixed.This means that the total number of units remains the same.

Alice:(Betty+Cecilia) ------ 1:3 -------9:27
Betty:(Alice+Cecila) ------1:8 ------- 4:32

Alice ----- 9 units
Betty ----- 4 units
Cecilia ----- 23 units

23 – 9 ---- 14
14 units ---- 60

Here we end up with 1 unit equals to $4.28.

This means we would be getting answers in decimals form.

Before I go on further,I would like you to check from the source what are the given answers.Also you may wish to confirm if the numbers in your question are in order.

Best wishes

Tks Tianzhu, the answer for (a) is $12 and (b) is $108. Confirm numbers in question are in order. Please advise

[tianzhu]

noob:

Tks Tianzhu, the answer for (a) is $12 and (b) is $108. Confirm numbers in question are in order. Please advise

Hi noob

If the answers are 12 and 108, two scenarios are likely

a)Instead of Alice paid $60 less than Cecilia, insert Alice paid $42 less than Cecilia.

Alice:(Betty+Cecilia) ------ 1:3 -------9:27
Betty:(Alice+Cecila) ------1:8 ------- 4:32

Alice ----- 9 units
Betty ----- 4 units
Cecilia ----- 23 units

23 – 9 ---- 14
14 units ---- 42

Here we end up with 1 unit equals to $3.

Betty ----- 4 units ------$12
Present ----- 36 units ----- $108

b)Instead of Alice paid 1/3 of the total amount of money paid by Betty and Cecilia, insert Alice paid 1/5 of the total amount of money paid by Betty and Cecilia.

Alice:(Betty+Cecilia) ------ 1:5 -------3:15
Betty:(Alice+Cecila) ------1:8 ------- 2:16

Alice ----- 3 units
Betty ----- 2 units
Cecilia ----- 13 units

13 – 3 ---- 60
10 units ---- 60

Here we end up with 1 unit equals to $6.

Betty ----- 2 units ------$12
Present ----- 18 units ----- $108

Best wishes

[Belle2011]

Hello

(1) I need some help in Speed and Time.
Muthu and Raju take the same route to school. Muthu’s average walking speed is 30 m/min faster than Raju’s. When Muthu reaches the school in 12 min, Raju has only walked 2/3 of the distance. Find the distance between the house and the school.

(2) I am also weak in nets for math. Do you have any tips or suggestions?

Thanks.

[tianzhu]

Belle2011:

(1) I need some help in Speed and Time.
Muthu and Raju take the same route to school. Muthu's average walking speed is 30 m/min faster than Raju's. When Muthu reaches the school in 12 min, Raju has only walked 2/3 of the distance. Find the distance between the house and the school.

Hi

For questions on Speed, it’s always good to start with a simple line diagram or distance/timeline.

In 1 min, Muthu walks 30 m faster than Raju.
In 12 minutes, Raju walks (12*30) or 360m faster than Raju.

When Muthu reached the school, Raju was 360m away from the school.
1 unit --- 360m
3 units ---- 1080m.

The distance between the house and the school is 1080m.

Best wishes

[Belle2011]

tianzhu:

Hi


For questions on Speed, it’s always good to start with a simple line diagram or distance/timeline.

In 1 min, Muthu walks 30 m faster than Raju.
In 12 minutes, Raju walks (12*30) or 360m faster than Raju.

When Muthu reached the school, Raju was 360m away from the school.
1 unit --- 360m
3 units ---- 1080m.

The distance between the house and the school is 1080m.

Best wishes

Thanks a lot. :celebrate:

[tianzhu]

Belle2011:

Thanks a lot. :celebrate:

Hi Belle2011

You're welcome.

Best wishes

[tianzhu]

Hi Belle2011


You may learn more about nets from these links.

http://www.youtube.com/watch?v=B_1JBtVNjzc
http://www.youtube.com/watch?v=qcyIIyWNuiQ&NR=1
http://www.youtube.com/watch?v=ktkzgsA3HZU

Best wishes

[Belle2011]

Hello,

John and Mary are brother and sister.
Mary says: I have twice as many brothers as sisters.
John says: I have as many brothers as sisters.
How many children are there in the family?
Thanking you in advance.