Q&A - P5 Math

[leelk]

Crazy this is so difficult! Are u sure this is for P2??

[jtparent]

MathIzzzFun:

jtparent:

Hi,


was lost in dealing fractions / %. Pls help on the following qs:

1. At a toy fair 40% of those present were boys . 8/15 of the remainder were girls & the rest were adults. There were 480 more boys than adults. How many more children than adults were there at the toy fair?

TIA

Hi

1. Boys = 40%, Girls + Adults = 60%
Girls = 8/15 x 60% = 32%, Adults = 60% - 32% = 28%

480 more boys than adults, so 40$ - 28% = 12% = 480, 1% = 40

Total children = 100% - 28% = 72%
72% - 28% = 44% = 44 x 40 = 1760

there were 1760 more children than adults.

cheers.

Thanks! You are great!

[jtparent]

MathIzzzFun:

jtparent:

Hi,


was lost in dealing fractions / %. Pls help on the following qs:

2. Last mth, David use $840 of his salary to buy a laptop. He spent 1/8 of the remaining salary on rent, $400 on food & saved the rest. The amount that he spent on food was $20 less than that spent on rent.
a. What was his salary?
b. What % of his salary did he save?


TIA

Hi

2. Amount spent on rent = 1/8 remaining salary = $400 + $20 = $420
So, total remaining salary (after spending $840) = 8 x $ 420 = $ 3360
a. Salary = $840 + $3360 = $ 4200

b. .. I think you can complete this

cheers.

Thanks! Appreciate your prompt reply!

[lizawa]

leelk:

Crazy this is so difficult! Are u sure this is for P2??

Ahem... \"P2\" refers to \"Paper 2\", not primary 2

[jtparent]

MathIzzzFun:

jtparent:

Hi,


was lost in dealing fractions / %. Pls help on the following qs:

3. Larry spent $60 less than 5/8 of his money on a MP3 player & $25 more than 7/9 of his remaining money on assessment books. After buying the assessement books, he still had $10 left.

a. How much money was left after Larry bought the MP3 player but before he bought the assessment books?
b. How much money did Larry have at first?

TIA

Hi

for this question.. work backwards..

After spending 7/9 remaining + $25 --> $10 left
So, $10 + $25 = $35 = 2/9 remaining money.
Money remaining (after spending on MP3) = 35/2 x 9 = $ 157.50

MP3 player = 5/8 of Larry's money - $60
Money remaining (after buying MP3) = 3/8 of Larry's money + $60
3/8 of Larry's money = $157.50 - $60 = $97.50
Larry's money = $ 97.50/3 x 8 = $ 260

cheers.

Hi,

sorry was confused on this wk backwards.

Is there other simpler method

[MathIzzzFun]

jtparent:

MathIzzzFun:

[quote=\"jtparent\"]Hi,


was lost in dealing fractions / %. Pls help on the following qs:

3. Larry spent $60 less than 5/8 of his money on a MP3 player & $25 more than 7/9 of his remaining money on assessment books. After buying the assessement books, he still had $10 left.

a. How much money was left after Larry bought the MP3 player but before he bought the assessment books?
b. How much money did Larry have at first?

TIA

Hi

for this question.. work backwards..

After spending 7/9 remaining + $25 --> $10 left
So, $10 + $25 = $35 = 2/9 remaining money.
Money remaining (after spending on MP3) = 35/2 x 9 = $ 157.50

MP3 player = 5/8 of Larry's money - $60
Money remaining (after buying MP3) = 3/8 of Larry's money + $60
3/8 of Larry's money = $157.50 - $60 = $97.50
Larry's money = $ 97.50/3 x 8 = $ 260

cheers.

Hi,

sorry was confused on this wk backwards.

Is there other simpler method [/quote]Hi

I am afraid you will have to find a method or \"devise\" a method to work backwards - there are quite a few ways ..

Here is one using branching:

http://i51.tinypic.com/23vl4s6.jpg\">

cheers.

[Superbugs]

Superbugs:

The figure below is not drawn to scale. The figure is made up triangles drawn within a rectangle. BY and CX are straight lines. The area if rectangle ABCD is 480cm2 and the area of triangle BXZ is 56cm2. Find the total area of the shaded parts.


Sorry that I do not know how to incorporate the diagram herein! Pls help. Tks

Anyone can help on this?

[2DMommy]

Need help with these two questions :


1) Mr Tan had 75 more apples than apples. after he had sold 4/5 of the apples and 3/4 of the oranges, he had 285 fruits left.
a) how many apples did he sell ?
B) What fraction of the fruits sold were oranges?

2) Alice gave $480 to her father and 25% of the remaining Salary to her mother. After giving 43% of her salary to her parents, she saved 15% of her salary.
a) How much did she spend?
b) How much did she give to her mother ?

Thank you .

[corneyAmber]

Superbugs:

Superbugs:

The figure below is not drawn to scale. The figure is made up triangles drawn within a rectangle. BY and CX are straight lines. The area if rectangle ABCD is 480cm2 and the area of triangle BXZ is 56cm2. Find the total area of the shaded parts.


Sorry that I do not know how to incorporate the diagram herein! Pls help. Tks

Anyone can help on this?

You can make a 640x640 jpg file and upload it using tinypic attached below in the editor to upload the picture.

[corneyAmber]

2DMommy:

Need help with these two questions :


1) Mr Tan had 75 more apples than oranges. after he had sold 4/5 of the apples and 3/4 of the oranges, he had 285 fruits left.
a) how many apples did he sell ?
B) What fraction of the fruits sold were oranges?

Thank you .

1. u = number of oranges
apples = u+75

u + (u+75) - 4/5(u+75) - 3/4u ->285
1/4u + 1/5(u+75) -> 285
1/4u + 1/5u + 15 -> 285
9/20u -> 270
u-> 600

a)number of apples sold = 4/5(600+75) = 540

b) oranges sold = 3/4(600) = 450
Total number of fruits = 600+600+75 = 1275
Fraction of oranges sold = 450/1275 = 18/51