Q&A - P3 Math

[PiggyLalala]

mama_10:

Janet & Rebecca saved a total of $387.6, Janet & Jennifer saved a total of $276.85. If Rebecca and Jennifer saved a total of $200.95, how much did Janet save?

Janet + Rebecca = 387.6
Janet + Jennifer = 276.85
Rebecca + Jennifer = 200.95

Therefore 2janet + 2rebecca +2jennifer = 865.40
Janet + rebecca + jennifer = 865.40/2 = 432.70

therefore rebecca = 432.70 - 200.95 = 231.75

[teh_oh]

PiggyLalala:

mama_10:

Janet & Rebecca saved a total of $387.6, Janet & Jennifer saved a total of $276.85. If Rebecca and Jennifer saved a total of $200.95, how much did Janet save?

Janet + Rebecca = 387.6
Janet + Jennifer = 276.85
Rebecca + Jennifer = 200.95

Therefore 2janet + 2rebecca +2jennifer = 865.40
Janet + rebecca + jennifer = 865.40/2 = 432.70

therefore rebecca = 432.70 - 200.95 = 231.75

Hi,
Is this P3 or P4 math? Thanks.

[cimman]

teh_oh:

PiggyLalala:

[quote=\"mama_10\"]Janet & Rebecca saved a total of $387.6, Janet & Jennifer saved a total of $276.85. If Rebecca and Jennifer saved a total of $200.95, how much did Janet save?

Janet + Rebecca = 387.6
Janet + Jennifer = 276.85
Rebecca + Jennifer = 200.95

Therefore 2janet + 2rebecca +2jennifer = 865.40
Janet + rebecca + jennifer = 865.40/2 = 432.70

therefore rebecca = 432.70 - 200.95 = 231.75

Hi,
Is this P3 or P4 math? Thanks.[/quote]well, Decimals isn't taught in P4 yet, till the later part of the year.

This looks like algebra to me. It will be interesting to see if modelling can solve this.

[corneyAmber]

http://i54.tinypic.com/2gvog1u.jpg\">

[corneyAmber]

teh_oh:

PiggyLalala:

[quote=\"mama_10\"]Janet & Rebecca saved a total of $387.6, Janet & Jennifer saved a total of $276.85. If Rebecca and Jennifer saved a total of $200.95, how much did Janet save?

Janet + Rebecca = 387.6
Janet + Jennifer = 276.85
Rebecca + Jennifer = 200.95

Therefore 2janet + 2rebecca +2jennifer = 865.40
Janet + rebecca + jennifer = 865.40/2 = 432.70

therefore rebecca = 432.70 - 200.95 = 231.75

Hi,
Is this P3 or P4 math? Thanks.[/quote]P3 can already draw such models and it starts by deducing which one has the smallest unit in order to see the representation clearly on the model.

[PiggyLalala]

Not really algebra. I would rather relate this question to question like

+ :imcool: = 8
:imcool: + :dancing: 10
+ :dancing: =6.
Find the value of .

We observe that if we add all, we will have 2( + :imcool:+ :dancing: ) = 24.
( + :imcool:+ :dancing: ) = 12
therefore = 12 -10 = 2.
Such questions are common in P2 assessment book.

[cimman]

PiggyLalala:

Not really algebra. I would rather relate this question to question like

+ :imcool: = 8
:imcool: + :dancing: 10
+ :dancing: =6.
Find the value of .

We observe that if we add all, we will have 2( + :imcool:+ :dancing: ) = 24.
( + :imcool:+ :dancing: ) = 12
therefore = 12 -10 = 2.
Such questions are common in P2 assessment book.

I would still say this is basic algebra. Just replace the symbols with x,y,z and you'll have algebra. Just because it is taught in P2 doesn't mean it is not algebra. They're teaching basic algebra in P2, just packaged differently with the symbols.
There's 3 unknowns, 3 equations and you're adding the 3 equations together, that's algebra with symbols. Well, x,y,z are symbols too that represents unknowns.

[ozora]

hi need help on the following question,

Q1. John had 1/3 as many red marbles as blue marbles. If he bought 12 red marbles, he would have 2/5 as many red marbles as blue marles. How many marbles did he have altogther?

[Concerndad]

Hi…ozora…



Q1. John had 1/3 as many red marbles as blue marbles. If he bought 12 red marbles, he would have 2/5 as many red marbles as blue marles. How many marbles did he have altogther?


Ans:

Before…
rm []
bm [][][]

After…(bought 12 red marbles)
rm [][]
bm [][][][][]

(the amt. of blue marbles remain the same…)
3 x 5 = 15units
(this is to make the ‘before’ n ‘after’ blue marbles have the same no. of units)

1 x 5 = 5units
(make the ‘before’ red marbles’ unit same as the ‘after’)

2 x 3 = 6units
(make the ‘after’ red marbles’ unit same as the ‘before’)

(the revise ‘before’ become…)
Before
rm [][][][][]
bm [][][][][][][][][][][][][][][]

(the revise ‘after’ become…)
After
rm [][][][][][]
bm [][][][][][][][][][][][][][][]

(the rm increase by 1unit)
6units - 5units = 1unit
1unit -> 12
20units -> 20 x 12 = 240

John has 240marbles altogether.

Hope this helps…
Those info in the brackets need not be in the answer…it is to help to make clear the model steps, I made.
rgds,
concerndad

[ozora]

Concerndad:

Hi..ozora...



Q1. John had 1/3 as many red marbles as blue marbles. If he bought 12 red marbles, he would have 2/5 as many red marbles as blue marles. How many marbles did he have altogther?


Ans:

Before...
rm []
bm [][][]

After...(bought 12 red marbles)
rm [][]
bm [][][][][]

(the amt. of blue marbles remain the same...)
3 x 5 = 15units
(this is to make the 'before' n 'after' blue marbles have the same no. of units)

1 x 5 = 5units
(make the 'before' red marbles' unit same as the 'after')

2 x 3 = 6units
(make the 'after' red marbles' unit same as the 'before')

(the revise 'before' become..)
Before
rm [][][][][]
bm [][][][][][][][][][][][][][][]

(the revise 'after' become...)
After
rm [][][][][][]
bm [][][][][][][][][][][][][][][]

(the rm increase by 1unit)
6units - 5units = 1unit
1unit -> 12
20units -> 20 x 12 = 240

John has 240marbles altogether.

Hope this helps...
Those info in the brackets need not be in the answer...it is to help to make clear the model steps, I made.
rgds,
concerndad

thanks
I used ratio but my nephew only p4 doesn;t know how to use ratio. Your model answer is a great help.
thanks again