Q&A - PSLE Math

[tianzhu]

Michaelia0816:

Pls help me!

Hi ah girl

Good Morning.

You put up two posts in such a short span of time, 1059h and 1126h.

Don’t push me so hard leh.

We seek your understanding to give the volunteers reasonable time, and also many of the volunteers here are parents who may not be able to solve all your questions.

I am just an old man, the burdens of life are challenging enough.

I prefer my trip in KSP to be a relaxing cruise along River Safari. As such, I don’t like to rush through solutions.

When I clicked on the link, it was a Speed question.

Are you referring to the Speed question or Ali question?

Best wishes

[Michaelia0816]

I want you to help me part (a) with the speed question as I dun understand and for the Ali question, which give me the answer, ( for checking)

[nounou]

:rotflmao: :rotflmao: :rotflmao:

:lovesite: :itwasntme: :goodpost:
:boogie: :rahrah:

tianzhu:

Michaelia0816:

Pls help me!

Hi ah girl

Good Morning.

You put up two posts in such a short span of time, 1059h and 1126h.

Don’t push me so hard leh.

We seek your understanding to give the volunteers reasonable time, and also many of the volunteers here are parents who may not be able to solve all your questions.

I am just an old man, the burdens of life are challenging enough.

I prefer my trip in KSP to be a relaxing cruise along River Safari. As such, I don’t like to rush through solutions.

When I clicked on the link, it was a Speed question.

Are you referring to the Speed question or Ali question?

Best wishes

[charsen]

Michaelia0816:

Michaelia0816:

Tianzhu,

Pls help with this question. I do not understood the (a) part by http://2.bp.blogspot.com/_NGNaLTzN5_U/SrxBdiupjrI/AAAAAAAADz0/SzuIy0v5zX0/s1600-h/Maths0609SA2P2NYSpeedQ17A.JPG.

1) Ali saved some money in the form of $2, $5 and $10 notes. The value of the $2, $5 and $10 was in the ratio of 3:10 : 5. After taking out 2/3 of the $2 notes and 16 of the $5 notes to pay for a trip to China ,he had $2400 left. Find the value of the $10 notes that he had saved. ( Can I ask for the last step, I not sure if it is $1550 or $775)

Pls help me!

Hi
I'm back.
For question 1,which part you do not understand?
For question 2,i would elaborate the question and from there,you can solve.
2/3 of the $2 notes means it is the quantity.But,it also means that it is 2/3 of the total value of $2.From here,the question is so called'chicken feed'.
Cheers

[charsen]

Shimmer:

Hi, need help on this please. Thanks in adv.


Clare counted the number of 10cents, 20cents and 50cents in the bank. The no. Of 10cents was 17 more 50cents. After spending 60% of the 10cents, 25% of 20cents and 18 50cents, she had equal for all coins. The no. Of 50cents now formed 40% of not spent.

A) How many 10cents coin at first ?
B) How much spend in all ?

Hi
There is an error in the question.The error is in the last sentence.The sentence structure of the last sentence is something wrong.Make the nesscary changes to the last sentence.

[charsen]

xiaotiao:

Can anyone help me to solve this problem, thanks!!!


The average weight of a group of boys is 50kg. If one more boy who weighs 76 kg joins the group, the average of weight will become 52kg. Find the number of boys in the group.

Hopefully a kind soul can do me a favour.

Hi
Assume that the number of boys in the group before adding the 76kg boy is n.
Difference in average--->52-50=2kg
76-52=24kg
Always remember that the extra part,which is 24 kg of the boy is equal to the increase which is (2xn)kg.
N-24/2=12 boys
Total boys --->12+1=13 boys(ANS)
By right,i could have drawn a model to make it clearer,but due to time constrain,i could not do .
Hope this works
Cheers

[charsen]

ms_lim:

Can help to explain how to solve this question?


http://i47.tinypic.com/v4ov3b.jpg\">

b)
pattern no. no.of white tiles
2 8 --->8x1
4 32--->8x4
6 72--->8x9
8 128---->8x16

If you find the difference of white tiles between each pattern no.,2to4 is 24 4to6 is40,72 to 128 is 56.
Notice the part (1,4,9 and 25).these are square numbers.
So,Nth pattern no. is 8x(n/2xn/2)
8x(30/2x30/2)=1800(ANS)

[cimman]

Shimmer:

Hi, need help on this please. Thanks in adv.


Clare counted the number of 10cents, 20cents and 50cents in the bank. The no. Of 10cents was 17 more 50cents. After spending 60% of the 10cents, 25% of 20cents and 18 50cents, she had equal for all coins. The no. Of 50cents now formed 40% of not spent.

A) How many 10cents coin at first ?
B) How much spend in all ?

looks like Singlish has finally found it's way in to Maths Problem Sums. :faint:

[tianzhu]

Michaelia0816:

I want you to help me part (a) with the speed question as I dun understand and for the Ali question, which give me the answer, ( for checking)

Hi

I believe this is a typical Speed question from past years papers.

You can use the Speed Triangle, Distance ----- Speed*time and the relationship between the position of Ali and Steve.

To calculate the starting time taken by Steven, there is more than one option.

Best wishes

http://farm9.staticflickr.com/8301/7947589604_f3d0dc949b_z.jpg\">

[charsen]

ms_lim:

Can help to explain how to solve this question?


http://i47.tinypic.com/v4ov3b.jpg\">

C)
I try to find the general rule and i found it for how to find the total no.of tiles.It is (pattern no.x2-1)x(pattern no.x2-1)+4.
I subtracted 4 from the total no. of tiles in each question.For example,29-4=25.
You know that 25 is a square root of 5,which is a odd no.So,if you subtract 4 from all the total no. of tiles,you get the square root of odd no.Next,you should find the odd no. of the square root you found.
take pattern 3 as an example.
29-4=25
5x5=25
i need to find the relation ship between the pattern no. and the odd no.So,I used the formula to find odd numbers which is 2n-1-->(3+3)-1=5
And there,i found the formula.
Cheers