tricky box question

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tricky box question

by tycoon_316 » Fri Jul 11, 2008 7:36 am
Image

17. The figure above shows the dimensions of a rectangular box that is to be completely wrapped with paper. If a single sheet of paper is to be used without patching, then the dimensions of the paper could be
(A) 17 in by 25 in
(B) 21 in by 24 in
(C) 24 in by 12 in
(D) 24 in by 14 in
(E) 26 in by 14 in

Please provide me explanation for this question thanks
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by VP_Jim » Fri Jul 11, 2008 4:23 pm
This one is easier than it seems. Since the paper is going to cover the box, the paper's area has to be at least equal to the surface area of the box. We can calculate the surface area of box = 432.

The only answer choice that is greater than or equal to 432 is answer choice B.
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by TRANGZON » Fri Jul 11, 2008 5:50 pm
I think something wrong 21 x 24 = 504

We just open the box 2x8x10 in order to have a rectangular 14x20

So the answer should be D

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by shrikantkamble » Fri Jul 11, 2008 8:46 pm
Hi,

Let us 1st find surface area of the box.

1) area of left side: 2 X 8 = 16
2) area of front Side : 2 X 20 = 40
3) area of top side : 8 X 20 = 160

Surface area of box = 2 (area 1 + area 2 + area 3)
= 2 ( 16 + 40 + 160 )
= 2 ( 216 )
= 432

Area of the paper should be atleast 432 to wrap the box.

A) 17 X 25 = 425
B) 21 X 24 = 504
C) 24 X 12 = 288
D) 24 X 14 = 336
E) 26 X 14 = 364


Only available option is B.

Answer B is correct.
Thanks & Regards,
Shrikant