Q&A - PSLE Math

[tianzhu]

Hi


Under the topic of Speed, Time and Distance, P6 students learnt about the formula, Distance =Speed*Time. It’s important to understand the concepts behind the formula rather than applying it without much understanding.

There are many variations in questions on Speed, thus, sometimes students may find them challenging.

One common type of question is overtaking or catching up. In this type of question, two vehicles or travellers leave the same point in the same direction but starting at different times. They have different speed. The vehicle/traveller that started later is faster.

Since this is an 'overtaking/catching up' problem, we should take note that the distance covered by both vehicles/travellers is the same at the time of overtaking/catching up.

In this post, I’ll share two ways to solve such problems. Hope you’ll find them useful.

Two similar types of questions

Q1) A lorry travelled at an average speed of 72km/h from Pink Town to Happy Town. 50 minutes later, a van started out from the same point towards the same destination at an average speed of 90km/h, reaching Happy Town at the same time.
a. How long did the van take to travel from Pink Town to Happy Town?
b. If both the lorry and the van arrived at Happy Town at 4.05pm at what time did the lorry start out?

Q2) Mary and Ken travelled from Town A to Town B. Mary left Town A at 0915 and took 4h to reach Town B. Ken left Town A at 1000 and took 2h 45min to reach Town B. At what time did Ken pass Mary?

Best wishes

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[Muffins]

hi Tianzhu, just wanted to ask, who is that person in your model workings? Your DD?

[tianzhu]

Muffins:

hi Tianzhu, just wanted to ask, who is that person in your model workings? Your DD?

Hi Muffins

Who’s that girl? She is sweet, right?

No lah, I don’t have a DD.I found her photograph while searching for some cliparts in Microsoft website.

I like it very much, so I used it to brighten up my presentation. Maybe, I am salivating over the idea of having a daughter.

Best wishes

[Muffins]

tianzhu:

Muffins:

hi Tianzhu, just wanted to ask, who is that person in your model workings? Your DD?

Hi Muffins

Who’s that girl? She is sweet, right?

Ya, very kewt! :love:

Tianzhu:

No lah, I don’t have a DD.I found her photograph while searching for some cliparts in Microsoft website.

I like it very much, so I used it to brighten up my presentation. Maybe, I am salivating over the idea of having a daughter.

Best wishes

You too buddy...

[imacsg]

Hi, Is this the correct way of solving the question? Can explain why the x 7 and x 21? Tks!



Packets of assorted candies were sold in 2 different sizes - standard and large. The large packet contained twice as many candies as the standard packet. In the standard packet, the ratio of the number of coconut candies to the number of strawberry candies were 4:5. In the large packet, the ratio of the number of coconut candies to the number of strawberry candies to the number of toffee candies was 1: 2: 3. A family bought 1 standard and 1 large packet.

What was the ratio of the number of coconut candies to the number of strawberry candies to the number of toffee candies?

The family ate 21 candies. As a result, the ratio of the number of coconut candies to the number of strawberry candies to the number of toffee candies became 2: 3: 3. How many candies were left?




Ans: (a) 7 : 11: 9 (b) 168

http://www.postimage.org/image.php?v=PqxjnT9

[tianzhu]

Hi imacsg


I wanted to try it, but can’t read your image.

When I clicked at the image, I got a warning as follows
Opening this website may put your security at risk

Could you enlarge the image or use Flickr to as the storage media?

Best wishes

[imacsg]

sorry, as I a new, still trying to figure how to upload the pic. can u teach me?


Standard ( 1) Large (2)
C S C S T
4 5 1 2 3 x 3
4 5 = 9 3 6 9 = 18

7 11 9 x7 2 3 3 x21
49 77 63 =198 42 63 63 =168

198-168 = 21 ans 168

[imacsg]

http://www.flickr.com/photos/52713803@N03/4860305682/

[tianzhu]

Hi imacsg


I am sorry. I am still having problems reading your images.Maybe, you want to try to insert images via Flickr.

Please follow these steps

1) Do a print screen of the portion you want to upload.

2) Edit using Paint. Cut out the portion of the question you want to upload.

3) Save file in pictures

4) Go to Flickr (Free sign up as member) or other storage sites. Upload file. Select biggest/medium size. Right click to copy URL of image.

5) Coming back to Kiasuparents forum, click insert image button.

I don’t know why as I am having problems reading images from postimage since renewing my virus protection software

Best wishes

[imacsg]

http://www.flickr.com/photos/52713803@N03/4859718213/



http://www.postimage.org/image.php?v=aVjrqdi