Q&A - P3 Math

[Blur Baby]

vlim:

Blur Baby:

Hello Uncles and Aunties, can you please help me with this question? Thank you.



Siti and Mohan started counting at the same time. Siti counted on by hundreds from 2000. Mohan counted backwards by thousands. After 4 counts, they had reached the same number. What number did Mohan start counting from?

Hi Blur Baby, aunty vlim hereby try to help you since tianzhu not around now..

After 4 counts, Siti would be : 2000, 2100,2200, 2300
Since both reached the same number after 4 counts, so Mohan would be 2300 after counting backwards by thousands after 4 counts
2300, 3300, 4300,5300

so Mohan start counting from 5300.

Hope u understand my explanation

Thank you Aunty vlim.

[Blur Baby]

small:

Blur Baby:

One more question please? My test is tomorrow. Thank you.



Hope this helps.

3 similar files and 2 similar books cost $60. 2 such files and 3 such books cost $70. Find the cost of 1 file.

3 files and 2 books cost $60 --------(1)
2 files and 3 books cost $70 -------(2)

So:
5 files and 5 books cost $130
1 file and 1 book cost $26
2 files and 2 books cost $52 -------(3)


From (1):

3 files and 2 books = 1 file + 2 files and 2 books
$60 = 1 file + $52
1 file = $8

1file cost $8

Thank you Uncle Small.

[DinoKing]

pertunia wrote:

small wrote:
Hassan has some pokemon cards to share among his friends. If he gives each friend 6 pokemon cards, he will have 5 cards left. If he gives each friend 8 pokemon cards, he will be short of 7 pokemon cards. How many pokemon cards does Hassan have?

Gap : 5+7 = 12

Different = 8 - 6 = 2
12 / 2 = 6 friends

From red font :
6 cards x 6 + 5 cards
= 41 cards

Hassan have 41 pokemon cards altogether.





Hi small,

Can you please explain why you use gap = 5+7? I am missing something here. Thanks.

And thanks to all the others who help with the answers. Really appreciate it.



Hi pertunia,

I am using Inference Approach to solve this, learned this from my son.


Alternatively you can refer to Tianzhu's solution on other question.

http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=280&postdays=0&postorder=asc&start=2490

Hi, can we use the above Inference Approach to solve below question (Ai Tong 2010 CA1 paper):Mrs Chan has more than 50 sweets. If she puts them in packets of 7, she has 5 sweets left.  If she puts them in packets of 9, she has 6 sweets left.  How many sweets does Mrs Chan have?  (provided ans is 96).If yes, is it okay to show me how to derive the answer?  Thank you very much. 

[tianzhu]

Hi DinoKing


I am not too sure about the “Inference Approach”, maybe small could elaborate more on it.

In this question, you cannot use” Gap and Difference” concept as the number of sweets and packets is not fixed.

As stated in the question, “Mrs Chan has more than 50 sweets”. So the exact number of sweets she has is not known in the beginning.Hence we use the “Multiples Method”

Start with multiples of 7 and 9 which are greater than 50.The common number after listing in a tabulated form is the least number of sweets Mrs Chan has.

Hope this helps.

Best wishes

http://farm6.static.flickr.com/5213/5493532691_b7a210144b_b.jpg\">

[DinoKing]

Hi Tianzhu,


My DD teacher has taught her class to use this "gap and different" concept to tackle this "kind of problem" and she is stuck with this question and couldn’t understand why is it so…

Base on yr explanations, we could use this "gap and different" concept in the "pokemon cards" question as the number of people and pokemon cards is fixed, right?

Sorry, my last question, why does the gap / different = number of people? (sorry my Maths is not good). I asked my DD and her reply is "my teacher said so…" :<

Really appreciate your help. Thank you very much.

[tianzhu]

DinoKing:

Hi Tianzhu,

My DD teacher has taught her class to use this \"gap and different\" concept to tackle this \"kind of problem\" and she is stuck with this question and couldn't understand why is it so...

Hi DinoKing

Good Afternoon.

You’ve used an interesting term “this kind of problem\". With this, it only means one needs this kind of strategy to solve this kind of problem.

It’s good to know that there is always more than one way to solve a problem.

Maths questions are not foot prints on concrete which has hardened but foot prints left on sand which can be easily erased. Questions may look similar but tweaked to make them more interesting.

“Gap and Difference” concept may be applicable to a range of questions but it cannot be applied to your question.

However, Multiples Method may be applied to questions which could be solved by GD, for example the you may use the Multiples Method to solve the Pokemon question.

Meanwhile, take a look at these questions.

Q1 and Q2 are common question found in primary maths, you may use Multiples Method or Gap and Differences Method to solve it.

Q3 is a similar type of question but given a slight tweak. It is quite an interesting one.

Q1) Xie Ming Ming had some oranges and some boxes. When she put 12 oranges in each box, she had 35 oranges left over. When she put 15 oranges in each box, she was short of 55 oranges.
a) How many oranges did Xie ming ming have?
b) How many boxes did she have?

Q2) A box of apples is shared among some people. If each person gets 5 apples, there will be 4 apples left. If each person gets 6 apples, there will be a shortage of 5 apples. How many people are there?

Q3) Guo Cong Ming distributed a packet of sweets among a group of pupils. If he gave out 11 sweets to each pupil, the last pupil received only 6 sweets. If he gave out 8 sweets to each pupil, there would be 34 sweets left over.
A. How many pupils were there?
B. How many sweets were there?

Best wishes

[DinoKing]

Hi Tianzhu, have a pm for you. Pls check. Thanks[/b]

[tianzhu]

DinoKing:

Hi Tianzhu, have a pm for you. Pls check. Thanks[/b]

Hi DinoKing

Good Morning

I've replied your PM.

Best wishes

[DinoKing]

Hi Tianzhu, received your pm. Really appreciate your help. Thank you and enjoy your weekends.

[tianzhu]

DinoKing:

Hi Tianzhu, received your pm. Really appreciate your help. Thank you and enjoy your weekends.

Hi

You're welcome.

Best wishes