Q&A - PSLE Math

[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.

[tianzhu]

Hi


You may use a problem solving heuristics known as Use a Diagram to create a pictorial description of the problem.

This helps the kids to see and understand the question.

Best wishes

http://farm6.static.flickr.com/5161/5208449974_c0a1bcc3d8_b.jpg\">

[noob]

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

many thanks

[Belle2011]

tianzhu:

Hi

You may use a problem solving heuristics known as Use a Diagram to create a pictorial description of the problem.
This helps the kids to see and understand the question.
Best wishes
http://farm6.static.flickr.com/5161/5208449974_c0a1bcc3d8_b.jpg\">

Thanks for sharing such a beautiful diagram. But I still can't figure out why the answer is 7 children.
Thanks.

[tianzhu]

Belle2011:

But I still can't figure out why the answer is 7 children.

Hi

Each image represents a boy or a girl (brothers and sisters).

Count the number of children.They add up to 7.

Mary has 2 sisters and 4 brothers --- This fulfills the condition --- Mary says: I have twice as many brothers as sisters.

John has 3 brothers and 3 sisters ---- This fulfills the condition --- John says: I have as many brothers as sisters.

Best wishes