Q&A - PSLE Math

[3Boys]

csc:

AnnT2009:

Hi,

I chanced upon this website recently. Need help to solve this question,

Amy took 3 hours to travel from Town P to Town Q. Pansy took 2 hours to travel from Town Q to Town P. Both of them started travelling at 9am. At what time did they pass each other?

Thanks and happy new year.

Let me try.

In 1 hour, Amy covered 1/3 of distance.
In 1 hour , Pansy covered 1/2 of distance

In 1 hour both covered 1/3 + 1/2 = 5/6 of distance

5/6 of distance ====== 1 hour
6/6 of distance ====== 1 1/5 hour = 1 hour 12 minutes

Therefore , they passed each other at 10.12 am.

Hope I'm right.

Maybe I'm just old but I find this new way of doing math just completely crazy. :?

[tianzhu]

Maths Questions from http://www.channelnewsasia.com/discussion/forum.htm


1. Two sisters, Melissa and Nicole, started brisk-walking at 6.45a.m. from their house to a nearby park. Melissa walked at an average speed of 90m/min while Nicole's average speed was 60m/min. After arriving at the park, Melissa rested for 10 minutes and then walked back home. If Melissa met Nicole at 7.40 a.m. on her return journey, what was the distance between their house and the park?

2. A group of people met at a party. Each person shook hands with everyone else. Mr Li shook hands with 3 times as many men as women. Mrs Li shook hands with 4 times as many men as women. How many men and how many women were there at the party?

[corneyAmber]

http://i3.photobucket.com/albums/y74/miamia2004/P6Mathwalkingdistance-1.jpg\">

[ChiefKiasu]

Wow… thanks for the great effort, ks2me!

[corneyAmber]

ChiefKiasu:

Wow... thanks for the great effort, ks2me!

Errr :oops: ....Chief...most importantly, is the answer correct?

[csc]

ks2me:

http://i3.photobucket.com/albums/y74/miamia2004/P6Mathwalkingdistance-1.jpg\">

Wow! Nice presentation but I came up with a different answer.

Time taken by Melissa shd be 55-10 = 45 min(after deducting 10 min rest)
Distance travelled by Melissa shd be 90 x 45 min = 4050 m

Hence, 4050 + 3300 =7350
7350/2 = 3675 m (distance between house and park)

What do you all think?

[tianzhu]

Q1)3675m is the correct answer.


Best wishes

[lizawa]

tianzhu:

Maths Questions from http://www.channelnewsasia.com/discussion/forum.htm


3. A group of people met at a party. Each person shook hands with everyone else. Mr Li shook hands with 3 times as many men as women. Mrs Li shook hands with 4 times as many men as women. How many men and how many women were there at the party?

Answer : no. of men = 16; no. of women = 5

See working :

http://www.postimage.org/image.php?v=gx2w0utS

[suiyuan]

Q47

Please help to establish the number pattern for Q47 in this link.
http://www.wendykoh.com/08/primary6-aitongca1-maths.pdf

[lizawa]

suiyuan:

Q47

Please help to establish the number pattern for Q47 in this link.
http://www.wendykoh.com/08/primary6-aitongca1-maths.pdf

Stage Squares
1 ===> 1
2 ===> square (2+1) - (1*4) = 5
3 ===> square (3+2) - ((2+1) *4) = 13
4 ===> square (4+3) - ((3+2+1)*4) = 25
5 ====> square (5+4) - ((4+3+2+1)*4) = 41
10 ===> square (10+9) - ((9+8+7+6+5+4+3+2+1) *4) = 181
100 ==> square (100+99) - ((99+98+97+...+1)*4) = 19801

nth stage == > square (n+(n-1)) - ((sum of (n-1, n-2, n-3....1)*4)

So you take the area of the whole figure at each stage- (no of squares cut of each edge * 4 edges).

to solve 99+98+...1 at primary level, no need to teach AP/GP,
just re-arrange 1+2+.. 99 and place them under 99+98... +1
So you get 1 term as (99+1), (98+2) etc. ie. each term is 100. Total 99 terms. So sum = (100*99) / 2