Q&A - P5 Math

[tianzhu]

YumYum:

Tianzhu, thanks.

Hi

You're welcome.

Best wishes

[happyheart]

tianzhu:

happyheart:

Thank you Tianzhu for answering this question. Sorry, I am trying to understand but just cannot get it. In the 2nd round, how do we establish the number of cards Muthu has? Could you explain further?

Hi

For the second transfer
2 units (2/3) -------- 660
3 units (3/3) -------- 990

Next, the first transfer
3 units (3/4) -------- 174
4 units (4/4) -------- 232

Best wishes

Thanks Tianzhu! I understand now

one question, Would you think this is a typical p5 question? I checked through DS worksheet and cannot find similar question to work on.

[happyheart]

Tianzhu, could you help me with one more question please?


3 children traded cards with one another.
At first, Eliza had more cards than Farhan and Michelle had 2 times as many cards as Farhan. After Farhan bought another 33 cards. Michelle lost half what she ha and Eliza lost 14 cards, Farhan now had 6 more cards than Eliza. In the end, the children had a total of 150 cards. How many cards did each child have at first?

[tianzhu]

happyheart:

Tianzhu, could you help me with one more question please?


3 children traded cards with one another.
At first, Eliza had more cards than Farhan and Michelle had 2 times as many cards as Farhan. After Farhan bought another 33 cards. Michelle lost half what she ha and Eliza lost 14 cards, Farhan now had 6 more cards than Eliza. In the end, the children had a total of 150 cards. How many cards did each child have at first?

Hi

You may present the solution using MD or using units.

Consider the end scenario first.

Michelle ------ 1 unit

Farhan ------ 1 unit + 33

Eliza ------- 1 unit + 27 (Farhan now had 6 more cards than Eliza.)

3 units + 33 + 27 ------- 150

3 units -------- 90

1 unit ------- 30

In the beginning

Michelle ------ 2 units -------- 2*30 --------- 60

Farhan ------ 1 unit ------ 30

Eliza ------- 1 unit + 27 + 14 -------- 30 + 27 + 41 -------71

Best wishes

[tianzhu]

happyheart:

Thanks Tianzhu! I understand now

one question, Would you think this is a typical p5 question? I checked through DS worksheet and cannot find similar question to work on.

Hi

Where did you get this question from?

From my experience during my kid's PSLE, questions involving \"Working Backwards\" are popular.

Best wishes

[the shadowed snake]

Hi I need help

John and Rauf take 4 days to build a model train. Rauf and Sean take 6 days to build the same train while John and Sean take only 3 days. How long would the three of them take to build the same model train?
what is the answer! :?: :?: :?: :?:

[tianzhu]

the shadowed snake:

Hi I need help

John and Rauf take 4 days to build a model train. Rauf and Sean take 6 days to build the same train while John and Sean take only 3 days. How long would the three of them take to build the same model train?
what is the answer! :?: :?: :?: :?:

Hi

A common multiple of 4,6 and 3 is 12.

John and Rauf
4 days -------- 12 units
Hence 1 day ------- 3 units

Rauf and Sean ------- 2 units/day

John and Sean ------- 4 units/day

Add up the units ,(2+3+5) ------- 9

Take note that the names are repeated twice.

Therefore,

John , Rauf and Sean ------ 9/2 ------- 4.5 units

12/4.5 ------- 2 days and 16 hours

Best wishes

[the shadowed snake]

tianzhu:

the shadowed snake:

Hi I need help

John and Rauf take 4 days to build a model train. Rauf and Sean take 6 days to build the same train while John and Sean take only 3 days. How long would the three of them take to build the same model train?
what is the answer! :?: :?: :?: :?:

Hi

A common multiple of 4,6 and 3 is 12.

John and Rauf
4 days -------- 12 units
Hence 1 day ------- 3 units

Rauf and Sean ------- 2 units/day

John and Sean ------- 4 units/day

Hi tianzhu
As I am a student, I did not understand how did you get 4 days -------12 units
pls explain further
:thankyou:

[tianzhu]

the shadowed snake:

Hi tianzhu
As I am a student, I did not understand how did you get 4 days -------12 units
pls explain further
:thankyou:

Hi

Good Morning.

I am working out in units because I want to avoid working with fractions.

Approach 1 ------ Whole number

A common multiple of 4, 6 and 3 is 12.

We choose 12 because it is the lowest common multiple of 4, 6 and 3.

You can also use 24 or any other multiples of 12.

Let’s assume it takes 12 units to complete the model train.

John and Rauf take 4 days to build a model train.

4 days -------- 12 units

Hence 1 day ------- 3 units

Similarly,

Rauf and Sean ------- 2 units/day

John and Sean ------- 4 units/day

Add up the units ,(2+3+5) ------- 9

Take note that the names are repeated twice.

Therefore,

John , Rauf and Sean ------ 9/2 ------- 4.5 units

12/4.5 ------- 2 days and 16 hours

This question can also be tackled using fractions.

Approach 2 ----- Fractions

In 1 day, John and Rauf will complete 1/4 of the model train.

1 day, Rauf and Sean will complete 1/6 of the model train.

1 day, John and Sean will complete 1/3 of the model train.

1/4 +1/6 + 1/3 -------- 18/24

As you can see, the names are repeated twice, so we need to divide 18/24 by 2

This gives 3/8.

In 1 day, the three of them will complete 3/8 of the train.

Hence they will take 8/3 or 2 days and 16 hours to complete the model train.

Best wishes

[beanbear]

I have such a struggle with the following type of problem sums. Is there a particular approach to such sums? What is the critical thing to understand about such problems?


(1) Mr Lim bought 4 pears & 5 lemons. Mr Tan bought 5 pears and 4 lemons. Mr Tan paid 20cents more than Mr Lim. If Mr Lim paid $4.40, how much did 4 pears cost?

(2) 5 similar files cost $3 more than 3 similar pens. Mrs Lee purchased 3 files and 6 pens for $17.40. What was the cost of each file?