Q&A - PSLE Math

[bobsg01]

Thank you ksi and MathIzzzFun for the concise explanation.


http://i51.tinypic.com/mx08px.gif\">

[Hifive]

Hi


I refer to the PSLE exam questions booklet.
Need help on the solution provided :

why 12 / 0.8 ?

Pls refer to :
http://www.flickr.com/photos/62186744@N04/5915210246/

or is there an alternative method of solution?

Thanks in advance.

[MathIzzzFun]

Hifive:

Hi


I refer to the PSLE exam questions booklet.
Need help on the solution provided :

why 12 / 0.8 ?

Pls refer to :
http://www.flickr.com/photos/62186744@N04/5915210246/

or is there an alternative method of solution?

Thanks in advance.

Hi

Since Tap A and Tap B are flowing at the same rate, volume of water flowing into the respective tanks will be the same.

Ratio of increase in height in Tank A to that in Tank B
= 50 x 20 : 60 x 10
= 5 : 3
= 5u : 3u

Height in Tank B = 1/3 x 36 cm = 12 cm

So 2u = 12cm, 1u = 6cm.

The height of water level in both tanks will be 5u = 5 x 6cm = 30cm

Volume of water in Tank A = 30 cm x 60 cm x 10 cm = 18l
So, time taken = 18/1.2= 15 min.

cheers.

[stary]

Thanks ksi!!!

[Hifive]

Hi MathIzzzFun


Many thanks for your explanation to my question.

Cheers

[MathIzzzFun]

Hifive:

Hi MathIzzzFun


Many thanks for your explanation to my question.

Cheers

Hi Hifive,

u r welcome

Regarding your question : “why 12 / 0.8?” - Every minute, the water level tank A will be 0.8cm higher than that in tank B. Since tank B had a headstart of 12 cm, in order for water level in tank A to be the same as in tank B, it must make up for this headstart of 12cm, so 12cm/0.8cm/min = 15 min.

cheers.

[Hifive]

Hi MathIzzzFun


Yes, now I can understand! Thanks so much!

[bobsg01]

P6 Problem


Thanks in advance for any help.

http://i55.tinypic.com/2zjdgt0.jpg\">

[MathIzzzFun]

Hifive:

Hi MathIzzzFun


Yes, now I can understand! Thanks so much!

Hi Hifive,

u r welcome

cheers.

[MathIzzzFun]

bobsg01:

P6 Problem


Thanks in advance for any help.

http://i55.tinypic.com/2zjdgt0.jpg\">

Hi

Initially, Mr Tan had 5u.
He sold 40% = 2u, and was left with 60% = 3u = 270, 1u = 90

a) Mr Tan sold 2u = 2 x 180 = 180 items

Number of items bought by Peter = 40% x 180 = 72

b) Number of items Peter had at first = 270 - 72 = 198

cheers.