Cube-->Cuboid

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Cube-->Cuboid

by harsh.champ » Sun Feb 07, 2010 12:01 pm
78 identical cubes each with 2 cm edge are joined together to form a cuboid. If the perimeter of the base of the cuboid is 64 cm, then the number of cubes along the height of the cuboid is

(A)3
(B)6
(C)2
(D)4
(E)Cannot be determined

The correct answer is C.
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by shashank.ism » Sun Feb 07, 2010 12:06 pm
harsh.champ wrote:78 identical cubes each with 2 cm edge are joined together to form a cuboid. If the perimeter of the base of the cuboid is 64 cm, then the number of cubes along the height of the cuboid is

(A)3
(B)6
(C)2
(D)4
(E)Cannot be determined

The correct answer is C.

Let A & B be the no. of cubes on side of cuboid and C be the no. on height of cuboid
so total no = A*B*C = 78
Also perimeter = 64
--> 2 (2A+2B) = 64
--> A+B =16
Now 78 = 13* 3*2 on factorization
and 13+3 =16 so C=2

Hence,The correct answer is C.[/quote]
Last edited by shashank.ism on Sun Feb 07, 2010 2:01 pm, edited 1 time in total.
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by ajith » Sun Feb 07, 2010 12:40 pm
harsh.champ wrote:78 identical cubes each with 2 cm edge are joined together to form a cuboid. If the perimeter of the base of the cuboid is 64 cm, then the number of cubes along the height of the cuboid is

(A)3
(B)6
(C)2
(D)4
(E)Cannot be determined

The correct answer is C.

say a,b,c are the num of the cubes on the each of the side of the cuboid

abc =78
a+b = 16

abc = 13*2*3

since a,b,c all are integers

a =13, b =3 and c =2 is one solution
a =3, b =13 and c =2 us another
c=2 in any case
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by onedayi'll » Sun Feb 07, 2010 12:56 pm
shashank.ism wrote:
harsh.champ wrote:78 identical cubes each with 2 cm edge are joined together to form a cuboid. If the perimeter of the base of the cuboid is 64 cm, then the number of cubes along the height of the cuboid is

(A)3
(B)6
(C)2
(D)4
(E)Cannot be determined

The correct answer is C.
The correct answer is C.
[/quote]


shashank.ism,

You're not providing any explanation just writing the correct answer....
That's looks like you're doing copy and paste.

I think its not the proper way.

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by onedayi'll » Sun Feb 07, 2010 1:03 pm
ajith wrote:
harsh.champ wrote:78 identical cubes each with 2 cm edge are joined together to form a cuboid. If the perimeter of the base of the cuboid is 64 cm, then the number of cubes along the height of the cuboid is

(A)3
(B)6
(C)2
(D)4
(E)Cannot be determined

The correct answer is C.

say a,b,c are the num of the cubes on the each of the side of the cuboid

abc =78
a+b = 16

abc = 13*2*3

since a,b,c all are integers

a =13, b =3 and c =2 is one solution
a =3, b =13 and c =2 us another
c=2 in any case



Hi,

How did u got a+b = 16?

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by ajith » Sun Feb 07, 2010 1:05 pm
onedayi'll wrote:
ajith wrote:
harsh.champ wrote:78 identical cubes each with 2 cm edge are joined together to form a cuboid. If the perimeter of the base of the cuboid is 64 cm, then the number of cubes along the height of the cuboid is

(A)3
(B)6
(C)2
(D)4
(E)Cannot be determined

The correct answer is C.

say a,b,c are the num of the cubes on the each of the side of the cuboid

abc =78
a+b = 16

abc = 13*2*3

since a,b,c all are integers

a =13, b =3 and c =2 is one solution
a =3, b =13 and c =2 us another
c=2 in any case



Hi,

How did u got a+b = 16?
Perimeter =64 cm and each cube has 2cm breadth

so 2*a*2cm+2*b*2cm =64
4(a+b) =64
a+b = 16
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