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 Forum Index >  Test Paper Related >  Primary 4 Matters
 Ai Tong SA1 P4 Maths
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By: pearldyn (offline)  Monday, April 12 2010 @ 08:29 AM CDT (Read 1892 times)  
pearldyn

Hello all,

Can anybody help me with this one?

Question number. 41

An MRT train was 2/5 full of passengers.
At the first station, 1/2 of the passengers alighted and 17 people boarded the train.
The train is now 1/4 full. How many passengers were there on the train at first?

Thanks in advance!

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By: pearldyn (offline)  Monday, April 12 2010 @ 10:03 AM CDT  
pearldyn

Can anyone help me on this?

There are 380 children at the Children's Carnival.
3/7 of the boys and 2/3 of the girls are watching the magic show.
The number of girls who are not watching the magic show is equal
to the number of boys who are not watching the magic show.
How many boys are at the Children's Carnival?

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By: pearldyn (offline)  Monday, April 12 2010 @ 10:08 AM CDT  
pearldyn

Quote by: pearldyn

Hello all,

Can anybody help me with this one?

Question number. 41

An MRT train was 2/5 full of passengers.
At the first station, 1/2 of the passengers alighted and 17 people boarded the train.
The train is now 1/4 full. How many passengers were there on the train at first?

Thanks in advance!



This question has been answered, sorry!

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By: kohkah (offline)  Tuesday, April 13 2010 @ 02:23 AM CDT  
kohkah

pearldyn
Can anyone help me on this?

There are 380 children at the Children's Carnival.
3/7 of the boys and 2/3 of the girls are watching the magic show.
The number of girls who are not watching the magic show is equal
to the number of boys who are not watching the magic show.
How many boys are at the Children's Carnival?



4/7 of boys = 1/3 of girls

redraw the model, replacing every 1 block of girl by 4 block of boys. Something like substituting in alegbra.

boys |-1-|-2-|-3-|-4-|-5-|-6-|-7-|
girls |-1-|-2-|-3-|-4-|-5-|-6-|-7-|-8-|-9-|-10-|-11-|-12-|

therefore, a total of 19 blocks = 380 children. each unit of block is = 20,
boys has 7 units, which is 140 boys.

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By: yeoky (offline)  Tuesday, April 13 2010 @ 05:10 AM CDT  
yeoky

Quote by: pearldyn

Hello all,

Can anybody help me with this one?

Question number. 41

An MRT train was 2/5 full of passengers.
At the first station, 1/2 of the passengers alighted and 17 people boarded the train.
The train is now 1/4 full. How many passengers were there on the train at first?

Thanks in advance!



1/4 ==> 1/5+17
4/4=1 ==> 4/5 +68
5/5 ==> 4/5 +68
1/5 ==> 68
2/5 ==> 134 (Answer)

Check,
2/5 ==>134/340
1/5==>68/340
68+17=85
85/340=1/4

Hope it helps.

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By: tanhuimin (offline)  Thursday, April 15 2010 @ 04:31 AM CDT  
tanhuimin

Question number. 41

An MRT train was 2/5 full of passengers.
At the first station, 1/2 of the passengers alighted and 17 people boarded the train.
The train is now 1/4 full. How many passengers were there on the train at first?


P4 is expected to solve this question by model drawing.


From model drawing, we can tells that
1 units --> 17
8 units --> 17 x 8 = 136

Answer : 136 passengers at first.
[img]

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By: pearldyn (offline)  Thursday, April 15 2010 @ 06:57 AM CDT  
pearldyn

Thanks HuiMin. Your model does really makes me understand it much clearer.

How about trying to solve the Carnival question?

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By: tanhuimin (offline)  Thursday, April 15 2010 @ 10:32 PM CDT  
tanhuimin

There are 380 children at the Children's Carnival.
3/7 of the boys and 2/3 of the girls are watching the magic show.
The number of girls who are not watching the magic show is equal
to the number of boys who are not watching the magic show.
How many boys are at the Children's Carnival?

In fact KohKah already solved the problem.

This question for P4 need to be solved by drawing model too.

Not watching show, Boy --> 4/7 of total no. of boys ----(a)
Not watching show, Girl --> 1/3 of total no. of girls ---(b)
since (a) and (b) has to be the same value, we show it in the model drawing

From the model,
Total no. of the small unit (with pink tick) = 7 + (4 x 3) = 19
1 unit --> 380 / 19 = 20
Total no. of boys = 20 x 7 = 140

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