Q&A - P5 Math

[tianzhu]

YumYum:

Hi, I need help with these qns.


1. Alice n Barry went shopping with a total of $475. After buying some items each, the amount Alice has left is 4 times the amount she spent and the amount Barry has left is thrice the amount he spent. Given that the couple has a total of $370 left, how much did each of them at first?

Thanks

Hi

Alice
Spent ------ 1u
Left ------- 4u

Barry
Spent ------ 1p
Left ------- 3p

4u + 3p ------- 370

1u + 1p ------- 105 (475 – 370)

3u + 3p ------- 315

1u ------- 370 – 315 --------55

1p ------- 105 – 55 ------- 50

Alice ------- 5*55 -------- 275

Barry ------- 4*50 -------- 200

Best wishes

[tianzhu]

YumYum:

2. In the first week of a fund raising campaign, Class 6A raised 4 times as much money as Class 6B. In the second week, class 6A raised another $180 while class 6B raised another $120. Given that class 6A managed to raise thrice as much money as class 6B within 2 weeks, what was the total amount raised by the 2 classes in the first week?

Hi

You may use “Units and Parts” or use MD.

At first
Class A : Class B ------- 4 units : 1 unit

Change
Class A : Class B ------- 180 : 120

In the end
Class A: Class B ------- 3 parts: 1 part

4 units + 180 ------- 3 parts

1 unit + 120 ------- 1 part
(x3)
3 units + 360 -------- 3 parts

4 units + 180 -------- 3 units + 360

1 unit ------- 180

Total amount@first week -------- 5*180 ------- 900

If you use MD, you'll see 3(1unit + 120) ------- 4 units + 180.This'll also gives 1 unit ------ 180.

Best wishes

[tianzhu]

YumYum:

Hi, one more qn:


Mary attempted all the 60 questions in a quiz and scored 195 marks. Given that 5 marks were awarded for each correct answer but 2 marks were deducted for each wrong answer, how many qns did Mary answer correctly?

Thanks

Hi

For every wrong answer, Mary lost (5+2) or 7 marks.

If all 60 answers were correct, Mary gained 300 (60*5) marks.

300 – 195 ------- 105

105/7 ------- 15

60 – 15 ------- 45

Mary answered 45 questions correctly.

Best wishes

[YumYum]

Tianzhu, thanks.

[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! :?: :?: :?: :?: