Q&A - PSLE Math

[tianzhu]

peggy:

Please assist with this.


There are more pupils in school A than school B. 30%of the pupils in school A is 45 more than 40% the pupils in school B. If 10% of the pupils in school A leaves to join school B, there will be 200 more pupils in school A than in school B.
a. How many pupils are there in school B?
B. How many percent less pupils are there in school B than school A?
Leave your answer as a fraction in the simplest form.

Thanks!

Hi

You may work with MD or units.

One possible way.

30% ------- 3/10 ------- 6/20

40% ------- 2/5 -------- 6/15

A common multiple of 2 and 3 is 6.

30% of the pupils in school A is 45 more than 40% the pupils in school B.

6 units ------- 6 units + 45

2 units -------- 2 units + 15

At first

School A ------- 20 units + 150

School B ------- 15 units

If 10% of the pupils in school A leaves to join school B, there will be 200 more pupils in school A than in school B.

In the end

School A ------- 18 units + 135

School B ------- 17 units + 15

18 units + 135 ------- 17 units + 15 + 200

1 unit ------- 80

Number of pupils@B ------- 15*80 ------- 1200

Number of pupils@A -------- 20*80 + 150 --------- 1750

1750 – 1200 -------- 550

550/1750*100% ------- 31 3/7%

Best wishes

[peggy]

Thanks, Tianzhu!

[kwcllf]

An Express train travels from Town A to Town B. A Normal train travels from Town B to Town A at the same time. When the two trains meet, the Express train has travelled 105km more than the Normal train. The two trains reached their destination in 6 hours and 10 hours respectively. What is the distance between the two towns?


Thanks.

[tianzhu]

kwcllf:

An Express train travels from Town A to Town B. A Normal train travels from Town B to Town A at the same time. When the two trains meet, the Express train has travelled 105km more than the Normal train. The two trains reached their destination in 6 hours and 10 hours respectively. What is the distance between the two towns?


Thanks.

Hi

For Speed questions, it’s useful to begin with a simple diagram.

A neat way is to use inverse proportion.

Time taken by express train: Time taken by normal train -------- 6:10 ------- 3:5

Distance covered by express train: Distance covered by normal train ------- 5:3

5-3 ------- 2

2 units ------- 105

1 unit ------- 52.5

Distance between two towns -------- 8*52.5 -------- 420 km

Best wishes

[kwcllf]

tianzhu:

kwcllf:

An Express train travels from Town A to Town B. A Normal train travels from Town B to Town A at the same time. When the two trains meet, the Express train has travelled 105km more than the Normal train. The two trains reached their destination in 6 hours and 10 hours respectively. What is the distance between the two towns?


Thanks.

Hi

For Speed questions, it’s useful to begin with a simple diagram.

A neat way is to use inverse proportion.

Time taken by express train: Time taken by normal train -------- 6:10 ------- 3:5

Distance covered by express train: Distance covered by normal train ------- 5:3

5-3 ------- 2

2 units ------- 105

1 unit ------- 52.5

Distance between two towns -------- 8*52.5 -------- 420 km

Best wishes

Thanks Tianzhu!

[zeemimi]

Can i find out if the child will be penalised for using algebra to solve Math questions?

[nounou]

Hi, can you please explain how did you get 9 units in \"in the end,

Susan --> 9 units --> 3/5 of Susan's sweets\"

:thankyou: :thankyou: :udaman:

MathIzzzFun:

2632parent:

Pls help!!!

On Sunday, Mrs Tan gave Devi and Susan some sweets. On Monday, Devi gave Susan 40% of her sweet. On Tuesday after Susan gave 2/5 of her sweets to Devi, both of them have the same number of sweets. If Susan had 112 sweets more than Devi at first,how many sweets did Devi have on Sunday?

Hi

in the end,
Susan --> 9 units --> 3/5 of Susan's sweets
Devi --> 9 units
Before Susan gave 2/5 to Devi,
Susan --> 15 units
Devi --> 3 units --> 3/5 of Devi sweets
At first,
Susan --> 13 units
Devi --> 5 units
So, 8 units ---> 112, 1 unit --> 14
Devi's sweets on Sunday --> 5 x 14 = 70

cheers.

[Winx5015]

Hi, really need help for the following questions.


1). Mr Lee took 7 hours to travel from Town A to Town B while Mr Wong took 8 hours to travel from Town B to Town A. Both of them did not change their speed throughout the journey. Both of them started off at the same time and moved towards each other. 3 hours later, they were 110km apart. What was the speed Mr Lee was driving?

2). There were 1000 students at the parade ground and indoor sports hall. 40% of the 600 students at the parade ground were girls. 60% of the students at the indoor sports hall were girls. After some students in both venues moved from one venue to the other, 30% of the students in the parade ground and 70% of the students at the indoor sports hall were girls. How many students were there in the indoor sports hall after the movement had taken place?

Thank you.

[tianzhu]

Winx5015:

2). There were 1000 students at the parade ground and indoor sports hall. 40% of the 600 students at the parade ground were girls. 60% of the students at the indoor sports hall were girls. After some students in both venues moved from one venue to the other, 30% of the students in the parade ground and 70% of the students at the indoor sports hall were girls. How many students were there in the indoor sports hall after the movement had taken place?

Thank you.

Hi

This question has been discussed before.

Best wishes

http://farm7.static.flickr.com/6070/6154555481_a1f43e1359_z.jpg\">

[tianzhu]

Winx5015:

Hi, really need help for the following questions.

1). Mr Lee took 7 hours to travel from Town A to Town B while Mr Wong took 8 hours to travel from Town B to Town A. Both of them did not change their speed throughout the journey. Both of them started off at the same time and moved towards each other. 3 hours later, they were 110km apart. What was the speed Mr Lee was driving?

Hi

This question has been discussed before.

http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280&start=4400

As in any question on “Speed”, it’s helpful to draw a simple diagram showing the relationships between two motorists.

Use a common multiple of 56 (7 and

Mr Lee

1h ------ 8 units

Mr Wong

1h ------7 units

In 1h they travelled 15 units

In 3h, they travelled 45 units.

56 – 45 ------11

11units ------ 110

1 unit ------ 10

8 units ------80

Mr Lee ------- 80km/h

Best wishes