O-Level Additional Math

[chrisu]

Thank you for your working and answer.

But my daughter's teacher gave the answer a p:q = 5:4 instead of 4:5.

I also got 4:5 as answer initially.

ChiefKiasu:

chrisu:

Can ignore this, I already got the workings and answer. Thank you.
[quote=\"chrisu\"]Please help A Sec.2 Maths question of Proportion.

Q) The scale of map P is 1:p and the scale of map Q is 1:q. If the same area is represented as 32sq.cm. on map P and 50sq.cm. on map Q, calculate the ratio p:q.

Kindly show workings as well.

Thank you.

1/p = sqrt(x/32) => p = sqrt(32/x)
1/q = sqrt(x/50) => q = sqrt(50/x)

=> p/q = sqrt(32/50) = sqrt(16/25)
=> p:q = sqrt(16) : sqrt(25) = 4 : 5[/quote]

[lost boy]

Please help me answer this question.


Find the smallest number,p,such that p/2 is a perfect square and p/3 is a perfect cube

[lost boy]

Please help me answer this question.


Find the smallest number,p,such that p/2 is a perfect square and p/3 is a perfect cube

[Jtutor]

lost boy:

Please help me answer this question.


Find the smallest number,p,such that p/2 is a perfect square and p/3 is a perfect cube

Hi,

p should be 2^3 x 3^4 = 648.

p/2 will give 2^2 x 3^4 which is a perfect square with powers that are multiples of 2.
p/3 will give 2^3 x 3^3 which is a perfect cube with powers that are multiples of 3.

Cheers!
Jtutor

[lost boy]

Thanks Jtutor

[Rhyll]

Hi jtutor,

I was looking at the math question ,
Do you mind explain how to know the power for 2 and 3.
is it by testing eg. 2^2 x 3^2 is a perfect square as well as perfect cube, then follow by guessing the power.

[Jtutor]

Rhyll:

Hi jtutor,

I was looking at the math question ,
Do you mind explain how to know the power for 2 and 3.
is it by testing eg. 2^2 x 3^2 is a perfect square as well as perfect cube, then follow by guessing the power.

Hi Rhyll,

Yes this question involves some \"guess & check\" technique.

To have a perfect cube, the power for 2 and 3 must be either 3, 6, 9, etc (multiples of 3). To have a perfect square, the power must be either 2, 4, 6, etc (multiples of 2).

Examples of perfect squares: 2^2 x 3^2, 2^2 x 3^4
Examples of perfect cubes: 2^3 x 3^3, 2^3 x 3^6
(Pls note that the powers for 2 and 3 need not be the same.)

Cheers!
Jtutor

[2DMommy]

Please help with these :


1) Look at the ( ) digit. If it is a ( ) or a ( ) , then original number is divisible by 5.

2)Look at the number formed by the ( ) digits only. If this number is divisible by 8, then the original number is divisible by 8.

3) ( ) up the digits in the ( ) positions. Then ( ) up the digits in the ( ) positions. If the difference between the two is ( ) or ( ), then the original number is divisible by 11.

[YumYum]

Hi, can anyone pls help with this Qn:


Give the reduced fraction representation of -2.05232323232323…

Thanks 

[YumYum]

quekcc:

YumYum:

Hi, can anyone pls help with this Qn:


Give the reduced fraction representation of -2.05232323232323......

Thanks 

Let y = 0.05232323....
then 100y = 5.23232323....
and 10000y = 523.232323...
-> 9900y = 523 - 5 = 518
so y = 518/9900 = 259/4950

Ans -2.0523232323 = -2 259/4950 or -10159/4950.

Thanks for the detailed explanation 