Pri 6 Maths Questions?

Question

Paul & Joyce had 25 comic books altogther.
Paul & Mark had 52 comic books altogether.
Mark had 4 times as many comics books as Joyce.
What is the difference between the number of books that Paul & Mark have?

The answer is 20.
But i am not sure how the answer is derived!
Pls help!!

Answer 1

In Singapore?.... Yes, they need visual presentation...You just have to present the model.

Here's the illustration:

Paul & Joyce had 25 comic books altogther.
___________ ____
|_____P_____| + |_J__| = 25

Paul & Mark had 52 comic books altogether.
____________ _________________
|_____P_____| + |________M_______| = 52

Mark had 4 times as many comics books as Joyce.
___________ ____ ____ ____ ____
|_____P_____| + |_J__||_J__||_J__||_J__| = 52


Since P is fixed having the same number of books, the difference between what Joyce has and Mark has is 52 minus 25 which is 27.

Here's the visual presentation:
____ ____ ____ ____
|_J__||_J__||_J__||_J__|

| <1> | <2> | <3> |<4> | (in portion)
____________ _____ 27
|_____P_____| + |_J__| |<------------------>|
|_____P_____| + |_________M_______|

Difference between what Mark has and Joyce has is 3 parts.

So Joyce has 27 divided by 3 = 9 books
and Paul has 25 - 9 = 16

which means Mark has 9 X 4 = 36 books.

So the difference between what Paul and Mark has is 36-16 = 20 books.

Hope that Help!

Answer 2

Let Joyce's book be x.
Therefore mark had 4x books.
Let paul have y books.

x+y=25
1st equation:
y=25-x

4x+y=52
2nd equation:
y=52-4x

1st equation=2nd equation
25-x = 52 -4x
Bring -4x to the left hand side of the equation and 25 to the right hand side.
The minus sign will become plus while the plus sign will become mins when brought to the other side fo the equation.
-x + 4x = 52-25
3x = 27
x = 27/3
= 9

Therefore joyce has x books which is 9, mark has 4x books which is 4 * 9 =36 and lastly, using the first equation (y=25-x), paul has 25-9 = 16 books.

Difference between paul and mark = 36 - 16
20



I did this sum using algebra. This might be a little hard for you to understand since you're still in P6, but you will learn this in sec sch. So I hope you can try to understand my method.

Anyway, I'm sorry that it's hard to use model's way of representing the answer...I believe that pri schs still teach the students the model way of solving this sum.

Answer 3

P + J = 25 Eq 1
P + M = 52 Eq 2
M = 4J Eq 3

The easiest is to substitute Eq 3 into Eq 2:

P + 4J = 52 Eq 4
P + J = 25 Eq 1

Subtract Eq 1 from Eq 4:

3J = 27
J = 9

Then just plug in to get P & M:

P + J = 25 ==> P = 25 - 9 = 16 From Eq 1
M = 4J = 36 From Eq 3

Then M - P = 36 - 16 = 20

That's the answer.

Answer 4

Iam sorry to say that Your question is wron!!!!!