DOOR out of 8 window panes

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kanha81: Master | Next Rank: 500 Posts; Posts: 431; Joined: Sat Jan 10, 2009 9:32 am; Thanked: 16 times; Followed by:1 members

DOOR out of 8 window panes

by kanha81 » Sat Feb 21, 2009 10:55 am

Eight square window panes of equal size are to be pieced together to form a rectangular French door. What is the perimeter of the door, excluding framing between and around the panes?

(1) The area of each pane is 1 square foot.

(2) The area of the door, excluding framing between and around the panes, is 8 square feet.

Need help in dissecting the problem. Thank you.

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Source: Beat The GMAT — Data Sufficiency | Sat Feb 21, 2009 10:55 am

ontopofit: Senior | Next Rank: 100 Posts; Posts: 68; Joined: Sun Dec 21, 2008 12:00 am; Thanked: 3 times

by ontopofit » Sat Feb 21, 2009 11:09 am

imo E

1) area of sq is 1 --> 2 rectangles are possible -- (4,2) and (8,1)
2) area of rect 8 ---> still 2 rectangles are possible -- (4,2) and (8,1)

hence E

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BuckeyeT: Senior | Next Rank: 100 Posts; Posts: 76; Joined: Sat Jan 24, 2009 3:00 pm; Thanked: 11 times; GMAT Score:730

by BuckeyeT » Sat Feb 21, 2009 11:15 am

If your putting together 8 squares of equal size to form a rectangle, there's only two possible formations that create rectangles (8x1 or 4x2, just done through sketching out).

(1) The area of each pane is 1 sq ft.
So, each side is 1 ft (since each pane is a square).

We're looking for the perimeter of the rectangle formed. So, let's plug pane side = 1 into each formation.

8x1 rectangle = 8 + 1 + 8 + 1 = 18 ft perimeter
4x2 rectangle = 4 + 2 + 4 + 2 = 12 ft perimeter

Since we're not sure which rectangle we're using, (1) is insufficient.

(2) The area of the door (rectangle formed) is 8 sq ft.
So, 8 sq ft = two possibilities.

(a) 4 ft x 2 ft
(b) 8 ft x 1 ft

But as we proved in (1), each of these formations has a different perimeter. So, (2) is insufficient.

Further, (2) didn't help us narrow down (1) or vice versa. We're still left wondering in what formation the squares form the rectangle door. So, the answer is E.

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avenus: Master | Next Rank: 500 Posts; Posts: 238; Joined: Tue Feb 10, 2009 8:44 am; Thanked: 9 times

by avenus » Sun Feb 22, 2009 9:26 am

Well, statement 1 and 2 give exactly the same information, don't they?

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sureshbala: Master | Next Rank: 500 Posts; Posts: 319; Joined: Wed Feb 04, 2009 10:32 am; Location: Delhi; Thanked: 84 times; Followed by:9 members