Q&A - PSLE Math

[MathIzzzFun]

comfy:

PiggyLalala:

[quote=\"comfy\"]I understand the step till extra books bought 20/2.5=8

But can explain the next step? why need to 50-8?

Let me try again.
8 extra books here mean if Mary buys 50 books, then it will be 8 more than the number of books she bought at first.

Hence the number of books that mary bought at first = 50 - 8 = 42.

Sorry i am not very good in explaining how i arrive at my answer. Hope you can understand. Maybe others can help. You can also look at Tianzhu's solution.

Thanks Tianzhu & PiggyLalala for solving the problem. Just need to get used to the way how it solved by both of u. Thinking whether it can be solved by model method as my dd is more familiar to that.[/quote]Hi

hope this helps...

http://i54.tinypic.com/2vbmxas.jpg\">

cheers.

[TT2]

Thanks carebear! Now I get it.

[stary]

Hi all, need help for the following questions


1) Mrs Yeo had 20% more books than Mdm Lim. Miss Tang had 40% fewer books than Mrs Yeo. Mrs Yeo and Mdm Lim gave Miss Tang some books in the ratio of 1:2. As a result, Miss Tang had 50% more books than before. Given that Miss Tang had 96 more books than Mdm Lim in the end, how many books did Miss Yeo give to Miss Tang?

2)Last Monday morning, Edward walked from home to school. For the first 2 minutes, he was walking at an average speed og 40m/min. When he realised that he was going to be late by 3 minutes, he quickly increased his speed by 10m/min. As a result, he was early be 1 minute. Find the distance between his home to his school.

[stary]

Next page is page 400!

[stary]

We’ve gone to the 400th page!!!

[carebear]

stary:

Hi all, need help for the following questions


1) Mrs Yeo had 20% more books than Mdm Lim. Miss Tang had 40% fewer books than Mrs Yeo. Mrs Yeo and Mdm Lim gave Miss Tang some books in the ratio of 1:2. As a result, Miss Tang had 50% more books than before. Given that Miss Tang had 96 more books than Mdm Lim in the end, how many books did Miss Yeo give to Miss Tang?

2)Last Monday morning, Edward walked from home to school. For the first 2 minutes, he was walking at an average speed og 40m/min. When he realised that he was going to be late by 3 minutes, he quickly increased his speed by 10m/min. As a result, he was early be 1 minute. Find the distance between his home to his school.

Managed to do 1st question only.


http://www.flickr.com/photos/63342911@N03/6093555012/

[carebear]

2nd question solved.

Sorry for the poor quality cos I am too tired :snooze:.

http://www.flickr.com/photos/63342911@N03/6093193929/

[stary]

Thanks carebear!!!

[SaPan]

tianzhu:

SaPan:

some workers arranged chairs in 18 short rows and 7 long rows.
each long row had 32 more chairs than short rows.
half of the chairs were arranged in long rows while 3/7 of the chairs in short rows.
remaining chairs are stacked in a corner.

How many chairs were arranged in rows?

Hi

Long rows (LR) ------ 7 units (1/2 of 14)
Short rows (SR) ------ 6 units (3/7 0f 14)
Stacked up chairs ------ 1 unit

6 units ------ 18SR
1 unit ------ 3SR

1LR ------ 1SR + 32
7LR ------ 7SR + (7*32) ------7SR + 224

You may use MD to compare
7SR + 224 ------- 18SR + 3SR
14SR ----- 224
1SR ----- 16
\t
1 unit ---- 3SR ----- 48
13 units ----- 13*48 -------- 624

Number of chairs (rows) ------ 624

Best wishes

thank you so much tianzhu. :salute:

[Snowball99]

carebear:

stary:

Hi all, need help for the following questions


1) Mrs Yeo had 20% more books than Mdm Lim. Miss Tang had 40% fewer books than Mrs Yeo. Mrs Yeo and Mdm Lim gave Miss Tang some books in the ratio of 1:2. As a result, Miss Tang had 50% more books than before. Given that Miss Tang had 96 more books than Mdm Lim in the end, how many books did Miss Yeo give to Miss Tang?

2)Last Monday morning, Edward walked from home to school. For the first 2 minutes, he was walking at an average speed og 40m/min. When he realised that he was going to be late by 3 minutes, he quickly increased his speed by 10m/min. As a result, he was early be 1 minute. Find the distance between his home to his school.

I think you should use the ratio of speed and time. (inversely related)


Speed:
4:5
Time:
5:4
The difference between the times is 4 minutes.
Thus, 1u time = 4 min
So,
5u= 20 min
Distance= 40m/min for 20 min
= 800m

Managed to do 1st question only.


http://www.flickr.com/photos/63342911@N03/6093555012/