Q&A - P4 Math

[Herbie]

Jamesbond:

MathIzzzFun:

[quote=\"Jamesbond\"]Tan is given a wire that is 12cm long and asked to form a 4 sided figure. The 4 sided figure formed should have 4 right angles inside the figure. What is the biggest area he can form?


1) 5 cm2
2) 8cm2
3) 9cm2
4)10cm2.

Pl give me the ans with explanation. Thx.

Hi

given the same perimeter, forming a square will give you the largest area - a proper proof is by using calculus, but you can do a simple listing to deduce this fact.

cheers.

According to me is ans 1 correct....pl help.[/quote]I tot the answer shld be 9cm2 (3x3)
Perimeter will be 3+3+3+3=12cm2.

[kiasuMay11]

Jamesbond:

tianzhu:

[quote=\"kiasuMay11\"]5/6 of the cakes sold for the week were chocolate cakes while the rest were vanilla cakes. How many more chocolate cakes than vanilla cakes did the bakery sell for the week?


Ans:124.
Pls explain why.

Hi

Please refer to your source, some information might be missing.

Best wishes

exactly....One more no r fraction shud b given.[/quote]ya... i was thinking the question is incomplete. having a hard time when my girl ask me how to get 124

[MathIzzzFun]

Jamesbond:

MathIzzzFun:

[quote=\"Jamesbond\"]Tan is given a wire that is 12cm long and asked to form a 4 sided figure. The 4 sided figure formed should have 4 right angles inside the figure. What is the biggest area he can form?


1) 5 cm2
2) 8cm2
3) 9cm2
4)10cm2.

Pl give me the ans with explanation. Thx.

Hi

given the same perimeter, forming a square will give you the largest area - a proper proof is by using calculus, but you can do a simple listing to deduce this fact.

cheers.

According to me is ans 1 correct....pl help.[/quote]Hi

answer is (3) 9 cm²

You can list the possible dimensions, and you will notice that the area will finally converge to 9 cm²
Possible dimensions of rectangle with perimeter 12 cm
- 1 cm x 5 cm --> 5cm²
- 2 cm x 4 cm --> 8cm²
- 2.5 cm x 3.5 cm --> 8.75 cm²
- 2.9 cm x 3.1 cm --> 8.99 cm²
- 3 cm x 3 cm --> 9 cm²

cheers.

[Jamesbond]

:thankyou: Mathizzzfun for ur explanation..... :rahrah:

[cmm]

Pls help with this question:


A B C D
1 2 3 4
8 7 6 5
9 10 11 12
16 15 14 13

In which column will the number 46 appear?

THanks in advance!

[Michell0328]

Help me!

1000x99+195-64+74=>>>?

[cmm]

Sorry, i tried to line the numbers up nicely but it’s not happening.


Column A: 1, 8, 9, 16
Column B: 2, 7, 10, 15
Column 3, 6, 11, 14
Column 4, 5, 12, 13

Accordingly to the teacher, there should be a formula to arrive at the answer rather easily…
Thanks!!

[kiasuMay11]

http://i47.tinypic.com/350vxqh.jpg\">


pls help. TY

[Mychildren]

Workings:

2x2=4
3x3=9
4x4=16
5x5=25
6x6=36
7x7=49
8x8=64
9x9=81

When 3 of the combination=115, its the area of each of the square tiles.
That is 9+25+81=115.

Length of biggest square is 9cm
Length of smallest square is 3cm
Ans: 9-3=6

[kiasuMay11]

Mychildren:

Workings:

2x2=4
3x3=9
4x4=16
5x5=25
6x6=36
7x7=49
8x8=64
9x9=81

When 3 of the combination=115, its the area of each of the square tiles.
That is 9+25+81=115.

Length of biggest square is 9cm
Length of smallest square is 3cm
Ans: 9-3=6

Got it.