Q&A - PSLE Math

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marcusya:

HI,

  Citrine bought twice as many pencils as notebooks and spent a total of $53.60. She spent $2.40 more on the notebooks than the pencils. Given that a notebook costs $1.90 more than a pencil, find the cost of a pencil.
The answer is 1.60 but i dont know the steps to solving this sum.
Thanks!

Hi,

HTH….

First, find the total cost for pencils as notebooks:
Total cost of pencils = ($53.60-$2.40)/2 = $25.60
total cost of notebooks = $53.60 - $25.60 = $28.00

Citrine bought twice as many pencils as notebooks, which means :
2 units of pencils = $25.60 (1 unit of pencils = $12.80)
1 unit of notebooks = $28.00


Given that a notebook costs $1.90 more than a pencil, so number of notebook in each unit will be ::

(Price of 1 unit of notebooks - Price of 1 unit of pencils ) / 1.90
= ($28.00-$12.80)/$1.90
= $15.20 / $1.90
= 8 (notebooks in a unit)

So there are 16 pencils altogether.
$25.60 / 16 = $1.60

The cost of a pencil is $1.60.

[ASK TalkMaths]

marcusya:

HI,

  Citrine bought twice as many pencils as notebooks and spent a total of $53.60. She spent $2.40 more on the notebooks than the pencils. Given that a notebook costs $1.90 more than a pencil, find the cost of a pencil.
The answer is 1.60 but i dont know the steps to solving this sum.
Thanks!

Hi marcusya,

I have solved your question. The solution is in the following link:
https://docs.google.com/viewer?a=v&pid=explorer&chrome=true&srcid=0B81le9JxERBGZWFlNjBlODktNTgzYi00MGY3LWI0MGQtODYyYzRhZmVmOGVj&hl=en_GB

Feel free to clarify with me if you any problems on my facebook page << Mod's Note - URL Removed according to forum's rules >>

[tianzhu]

mvmir26:

Thank you Tianzhu.

Hi

You’re welcome.

Wishing you the very best for PSLE 2011.

Best wishes

[Daddy]

Hi Tianzhu,


http://i56.tinypic.com/zvse95.jpg\">

Did not understand the chicken units is not the same size as ducks and quails? Which part of the question said that they are different. Thanks.

Most question I had asked for whole numbers. The units for different objects is the same size and make them equal to each othe?

I confusion on the chickens, duck and quail quesions. Please help?!! Thanks.

[Daddy]

Hi Tiazhu,


http://i52.tinypic.com/1058s5x.jpg\">

I do not understand that the model for chicken is not the same as duck and quail. Which part of the statement told that they are different? Please help!!

[tianzhu]

Daddy:

I do not understand that the model for chicken is not the same as duck and quail. Which part of the statement told that they are different? Please help!!

Hi

The boxes showing chicken eggs are different from those of ducks and quails because they belong to different sets of objects.

Best wishes

[Daddy]

Hi Tianzhu,


I still not understand.
Is it the chicken’s egg did not do a compare, Stand alone model?
Duck eggs compared with quail eggs, so their model units are the same.
Am I corrected?

Thanks

[Daddy]

Hi Tiazhu,

Is my answer corrected?

Jim and his sister shared some money. 1/3 of Jim's amount is 3/4 of his sister's share. If the difference in their share of money was $50, how much money did Jim have?

Jim [][][][][][][][][]
sister [][][][][][][][][][][][]
|------> $50
3u -> $50
1u -> 50/3
Jim -> 9u
= 9 x 50/3
= $150

[meremortal]

Daddy:

Hi Tianzhu,


I still not understand.
Is it the chicken's egg did not do a compare, Stand alone model?
Duck eggs compared with quail eggs, so their model units are the same.
Am I corrected?

Thanks

What was the question?

[tianzhu]

Daddy:

Hi Tianzhu,


I still not understand.
Is it the chicken's egg did not do a compare, Stand alone model?
Duck eggs compared with quail eggs, so their model units are the same.
Am I corrected?

Thanks

Hi

Take for example, John is three times as old as his son.
In MD, we draw 3 boxes for John and 1 box for his son.

In this question, there is a link or relationship between duck and quail eggs,. He sold 3 times as many quail eggs as duck eggs.
So, if duck eggs are represented by 2 boxes, then quail eggs are represented by 6 boxes.

The chicken eggs are of different sets of objects; hence the units are of different kind and measure.

Best wishes