Q&A - PSLE Math

[MathIzzzFun]

bobsg01:

Need some engligtenment on this answer.


In Total number of parts the figure has is 2 + 9 = 11 units

Why does it used 9 instead of 8 with minus 1 for Z? Confusing because they used 2 for X (which is minus 1 instead of 3). :?

Thanks for your kind assistant.

http://i53.tinypic.com/cltf5.jpg\">

http://i52.tinypic.com/2ivffh0.jpg\">

Hi bobsg01,

The ratio of the areas, A : B : C = 3 units : 4 units: 9 units, so 9 units is the total area of Z.

cheers.

[MathIzzzFun]

raghupavithra:

the cost to print a banner depends on the size of the banner. it also includes a fixed processing fee. A banner 5m long and 3m wide costs $75 to print.Another banner 4m long and 2m wide costs $47 to print


How much is the fixed processing fee?

how to solve the problem

Hi

hope this helps

http://i55.tinypic.com/2qm3t07.jpg\">

cheers.

[corneyAmber]

WS1234567:

Area of 1st banner: 5 x 3 = 15

Area of 2nd banner: 4 x 2 = 8
Difference in cost: $75 - $47 = $28
Difference in areas: 15 - 8 = 7
So, 7 units =$28
1 unit = $4
8 units = $4 x 8 = $32
Fix processing cost = $47 - $32 = $15

Dear WS1234567

I have edited your post. Please note that you are not allowed to advertise about your tuition service in any other threads apart from the the Directory of Tutors which has been set up and will take effect from today.

Read here for more info. Thanks.

http://www.kiasuparents.com/kiasu/forum/viewforum.php?f=31

[Dharma]

zsqchx:

Can someone help for this question. Thanks.


Candle A and Candle B are of the same length. Candle A, Which is broader, can burn for 5h while Candle B, the thinner candle, can burn for 4h. If both candles are lighted at the same time, how long does it take for Candle A to be twice as long left as Candle B?

For a fixed length of candle;
Time ratio for burning => Candle A : Candle B = 5 : 4
Ratio of burning rate => Candle A : Candle B = 4 : 5

Consider a fixed length time when the unburn section of Candle A is 2 times of that of Candle B
Ratio of burnt length : Candle A : Candle B = 4 : 5
4u + 2p = 5u + 1p [Total length of Candle A = Total length of Candle B]
1p = 1u
So, the total length of candles is 6u (4u + 2u = 6u)
For Candle A => Time taken to burn 6u is 5hrs
Time taken to burn 4u of Candle A = 4 x 5/6 = 10/3 hrs = 200 minutes
For Candle B => Time taken to burn 6u is 4hrs
Time taken to burn 5u of Candle B = 5 X 4/6 = 10/3 hrs = 200 mins

[raghupavithra]

wei quan has the same number of $10 notes and $50 notes what fraction of his money of his half of his $10notes?



how solve this sum pls help

[bobsg01]

MathIzzzFun:

bobsg01:

Need some engligtenment on this answer.


In Total number of parts the figure has is 2 + 9 = 11 units

Why does it used 9 instead of 8 with minus 1 for Z? Confusing because they used 2 for X (which is minus 1 instead of 3). :?

Thanks for your kind assistant.

http://i53.tinypic.com/cltf5.jpg\">

http://i52.tinypic.com/2ivffh0.jpg\">

Hi bobsg01,

The ratio of the areas, A : B : C = 3 units : 4 units: 9 units, so 9 units is the total area of Z.

cheers.

Hi MathIzzzFun, how about total area of X, isn't the area 3 instead of 2.

[MathIzzzFun]

bobsg01:

MathIzzzFun:

[quote=\"bobsg01\"]Need some engligtenment on this answer.


In Total number of parts the figure has is 2 + 9 = 11 units

Why does it used 9 instead of 8 with minus 1 for Z? Confusing because they used 2 for X (which is minus 1 instead of 3). :?

Thanks for your kind assistant.

http://i53.tinypic.com/cltf5.jpg\">

http://i52.tinypic.com/2ivffh0.jpg\">

Hi bobsg01,

The ratio of the areas, A : B : C = 3 units : 4 units: 9 units, so 9 units is the total area of Z.

cheers.

Hi MathIzzzFun, how about total area of X, isn't the area 3 instead of 2.[/quote]Hi bobsg01,

I have redrawn the figure into model diagram, hope it helps

http://i56.tinypic.com/mhtw0g.jpg\">

cheers.

[bobsg01]

Wow, it's easier to explain to my son now with this model diagram.


Thank you MathIzzzFun. :salute:

[Dharma]

bobsg01:

Need some engligtenment on this answer.


In Total number of parts the figure has is 2 + 9 = 11 units

Why does it used 9 instead of 8 with minus 1 for Z? Confusing because they used 2 for X (which is minus 1 instead of 3). :?

Thanks for your kind assistant.

http://i53.tinypic.com/cltf5.jpg\">

http://i52.tinypic.com/2ivffh0.jpg\">

Ratio of X : Y : Z = 3 : 4 : 9
Ratio of Y (Shaded) : Y(Unshaded) = 1 : 3
Ratio of X (Shaded) : X (Unshaded) = 1 : 2
Total area of figure = 2u +1u + 3u + (9u – 4u) = 11u
Total area of shaded portion = 1u
Fraction of unshaded portion = (11u -1u)/11u = 10/11

[bobsg01]

Thanks Dharma for alternative solution. :hi5: