Q&A - PSLE Math

[elishatan]

Thank you all for your replies. I really appreciate it!

[MathIzzzFun]

using :

sum of angles around a point = 360° &
sum of interior angles of a triangle = 180°

http://i43.tinypic.com/72f7y9.png\">

cheers.

[fullhope]

Hi , can anyone help the following question?

Every Saturday, John will go for his usual exercise. If he runs up 32 steps and walks up 68 steps , he will take 184 seconds. If he runs up 50 steps and walks up 50 steps, he will take 175 seconds, if he runs up the same rate throughout the whole exercise, how long will he take to run the 100 steps?

Thank you in advance

[MathIzzzFun]

fullhope:

Hi , can anyone help the following question?

Every Saturday, John will go for his usual exercise. If he runs up 32 steps and walks up 68 steps , he will take 184 seconds. If he runs up 50 steps and walks up 50 steps, he will take 175 seconds, if he runs up the same rate throughout the whole exercise, how long will he take to run the 100 steps?

Thank you in advance

pls see tianzhu's reply to your post on page 914 (bottom of page)
- http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280&start=9130

cheers.

[ozora]

Need guide to solve the following questions.

q1. in 20 years time, Tom’s age will be 34 less than twice Joan’s age.
If Joan is now 3 times older than Tom, what is Tom’s present age?

q2. A is the oldest among three people. When B’s age was twice of C’s age, A was 30 years old. When A’s age was twice of B’s age, C was 21 years old. How old was C when A was 62 years old.


the above questions, I have used models to get the answers as follows: Q1 . Tom (1 unit+20years)
Joan( 4unit +20 years) x 2
Tom is 2 years

q2. B (2 units +a)
C (1 unit +a)
A( 2units +a) x 2
therefore C was 35

Besides using models, any other alternative ways to solve the above methods?
thanks

[Mary Joy]

Hi everyone,


Need help in solving this question.

Mr and Mrs Lim left their house at the same time but travelled in opposite directions along a straight road.Mrs Lim drove at a speed which was 10 km/h slower than Mr Lim.30 min later,when Mr Lim reached his destination,he and Mrs Lim were 85 km apart.How far did Mrs Lim travel when Mr Lim reached his destination?

Thank you

:thankyou: :lovesite:

[tianzhu]

Mary Joy:

Hi everyone,


Need help in solving this question.

Mr and Mrs Lim left their house at the same time but travelled in opposite directions along a straight road.Mrs Lim drove at a speed which was 10 km/h slower than Mr Lim.30 min later,when Mr Lim reached his destination,he and Mrs Lim were 85 km apart.How far did Mrs Lim travel when Mr Lim reached his destination?

Thank you

:thankyou: :lovesite:

Hi

Start with a simple diagram.

In 1h, Mrs Lim was 10 km behind Mr Lim.

In 30 minutes, Mrs. Lim was 5 km behind Mr. Lim.

1 unit + 1 unit + 5 ------ 85

1 unit ------- 40

Distance covered in 30 minutes ------- 40 km (distance travelled by Mrs Lim)

Best wishes

[Mary Joy]

ozora:

Need guide to solve the following questions.

q1. in 20 years time, Tom's age will be 34 less than twice Joan's age.
If Joan is now 3 times older than Tom, what is Tom's present age?

q2. A is the oldest among three people. When B's age was twice of C's age, A was 30 years old. When A's age was twice of B's age, C was 21 years old. How old was C when A was 62 years old.


the above questions, I have used models to get the answers as follows: Q1 . Tom (1 unit+20years)
Joan( 4unit +20 years) x 2
Tom is 2 years

q2. B (2 units +a)


C (1 unit +a)
A( 2units +a) x 2
therefore C was 35

Besides using models, any other alternative ways to solve the above methods?
thanks

My answer for the first question is: Tom is 2 4/5 years old,and I used the model method too :?

[Mary Joy]

tianzhu:

Mary Joy:

Hi everyone,


Need help in solving this question.

Mr and Mrs Lim left their house at the same time but travelled in opposite directions along a straight road.Mrs Lim drove at a speed which was 10 km/h slower than Mr Lim.30 min later,when Mr Lim reached his destination,he and Mrs Lim were 85 km apart.How far did Mrs Lim travel when Mr Lim reached his destination?

Thank you

:thankyou: :lovesite:

Hi

Start with
a simple diagram.

In 1h, Mrs Lim was 10 km behind Mr Lim.

In 30 minutes, Mrs. Lim was 5 km behind Mr. Lim.

1 unit + 1 unit + 5 ------ 85



1 unit ------- 40

Distance covered in 30 minutes ------- 40 km (distance travelled by Mrs Lim)

Best wishes

hello thanks for your explanation but I do not understand the sequence: 1 unit +1 unit+5.can you explain it to me?

[tianzhu]

Mary Joy:

hello thanks for your explanation but I do not understand the sequence: 1 unit +1 unit+5.can you explain it to me?

Hi

Hope this helps.

Best wishes

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