Q&A - P5 Math

[TulipisPink]

HI MathIzzzfun, Thanks a zill ! You had coloured my white hairs! ha ha…

[TulipisPink]

Hi tianzhu

Thanks for the answer… but we are still very confuse abt this sum.

[tianzhu]

TulipisPink:

Hi tianzhu

Thanks for the answer.. but we are still very confuse abt this sum.

Hi

Since (J+A) is repeated in both sets of ratios, we shall make the number of units for (J+A) the same so as to enable us to make a comparison.

The total units showing the amount of money J and A had is 9 units.

For the second set of ratio, the total units showing (J+A)’s amount of money is 7 units (6+1).

A common multiple of 7 and 9 is 63.

Best wishes

[MathIzzzFun]

TulipisPink:

HI MathIzzzfun, Thanks a zill ! You had coloured my white hairs! ha ha...

haha.. I can start a natural hair restoration salon!

cheers.

[cimman]

TulipisPink:

Hi parents

Could you help to solve this maths question? Thanks.

Pupil B, J and A shared some money. The ratio of B's money to the total of J's and A's money is 4:9. A's share was 6 times J's. B had $95 more than J. How much money had A?

if you don't mind using simultaneous equations, here's a solution:
http://i47.tinypic.com/2v0d7v6.png\">

[Udon]

Appreciate your help, can someone teach me how to break down the question n analyze... :imdrowning:


Q1

Kenny has 1.4 times the number of pens Sarah has. When Sarah gives
144 pens to Kenny, the ratio of the number of pens she has to the number of pens Kenny has is 1:3. How many pens must Kenny give back to Sarah so that she will have twice as many pens as him?
(Hint: Change the decimal to a fraction and then to a ratio)


Q2

David and Sally each have some money. If David spends $38, the ratio of his money to Sally's money will become 2:5. If Sally spends $38, the ratio of David's money to her money will become 8:13. How much money does each child have?

[tianzhu]

Udon:

Appreciate your help, can someone teach me how to break down the question n analyze... :imdrowning:


Q1

Kenny has 1.4 times the number of pens Sarah has. When Sarah gives
144 pens to Kenny, the ratio of the number of pens she has to the number of pens Kenny has is 1:3. How many pens must Kenny give back to Sarah so that she will have twice as many pens as him?
(Hint: Change the decimal to a fraction and then to a ratio)


Q2

David and Sally each have some money. If David spends $38, the ratio of his money to Sally's money will become 2:5. If Sally spends $38, the ratio of David's money to her money will become 8:13. How much money does each child have?

Hi

Q1

The total number of units stays the same before and after.

At first
Kenny ------ 7 units
Sarah ------ 5 units.

When Sarah gives 144 pens to Kenny, the ratio of the number of pens she has to the number of pens Kenny has is 1:3.

Kenny ------ 3 units ------- 9 units
Sarah ------ 1 unit ------- 3 units

5 – 3 -------- 2
2 units ------- 144
1 unit ------- 72

How many pens must Kenny give back to Sarah so that she will have twice as many pens as him?

Kenny ------ 1 unit ------- 4 units
Sarah ------ 2 units ------- 8 units

9 - 4 ------ 5

72*5 ------- 360.

Q2

The total number of units stays the same in the two scenarios.

If David spends $38, the ratio of his money to Sally's money will become 2:5.

David:Sally ------- 2 : 5 (7) ------- 6:15 (21)

If Sally spends $38, the ratio of David's money to her money will become 8:13.

David:Sally ------- 8 : 13 (21)

2 units ------- 38
1 unit ------- 19

David ------- 8*19 --------152
Sally -------- 15*19 -------- 285

Best wishes

[Udon]

Thanks for the reply, but i do not understand how to calculate


Kenny....1 unit become 4 units
Sally......2 units become 8 units

------------------------------------------------------------------------------------------
How many pens must Kenny give back to Sarah so that she will have twice as many pens as him?

Kenny ------ 1 unit ------- 4 units
Sarah ------ 2 units ------- 8 units

9 - 4 ------ 5

72*5 ------- 360.

[php]

Udon:

Thanks for the reply, but i do not understand how to calculate


Kenny....1 unit become 4 units
Sally......2 units become 8 units

------------------------------------------------------------------------------------------
How many pens must Kenny give back to Sarah so that she will have twice as many pens as him?

Kenny ------ 1 unit ------- 4 units
Sarah ------ 2 units ------- 8 units

9 - 4 ------ 5

72*5 ------- 360.

From the first part of the working, the total number of units they have is 12 units....Kenny (9 units) and Sarah (3 units)

For Sarah to have twice as many pens as Kenny, it means Kenny will have 1 unit and Sarah will have 2 units, giving total of 3 units...

In order solve the problem, you will have to equate both equations to have the same number of total units...i.e. 12 units...

So you will have to multiply x 4 for the second equation to get a total of 12 units....

Kenny - 1 unit x 4 = 4 units
Sarah - 2 units x 4 = 8 units

For Kenny,
Before - 9 units
After - 4 units

The difference of 5 units is given to Sarah....
5 units x 72 = 360

Hope my explanation helps...

[tianzhu]

Udon:

Thanks for the reply, but i do not understand how to calculate

Kenny....1 unit become 4 units
Sally......2 units become 8 units

Hi

Good Morning.

P5 students should be comfortable with changing from decimals to fractions and ratios.

1.4 ------ 14/10 ------- 7/5

A student should note that the total number of units stays the same in the various scenarios. Perhaps a good way is understand is to imagine Kenny and Sarah inside a box. The exchanges between them take place inside the box. Nothing flows out of the box, hence the total number of pens they had stays the same.

I’ve attempted to show the flow of events in this slide, as you can see nothing more than equivalent ratios is required to solve this question.

Hope this helps.

Best wishes

http://farm8.staticflickr.com/7232/7218581850_f5c8b8288e_z.jpg\">