|
|
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized
for You
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
30 Sep 2015, 00:20
Kudos
Bookmarks
C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
55%
(hard)
Question Stats:
68% (02:41) correct
32%
(02:53)
wrong
based on 189
sessions
History
Date
Time
Result
Not Attempted Yet
A square piece of sailcloth is trimmed by 4 feet on one edge to form a rectangular piece, which is then cut in half to create two triangular sails. If the area of each of the sails is 240 square feet, what was the perimeter of the original piece of sailcloth?
A) 75 feet
B) 88 feet
C) 96 feet
D) 104 feet
E) 576 feet
A) 75 feet
B) 88 feet
C) 96 feet
D) 104 feet
E) 576 feet
30 Sep 2015, 09:21
Kudos
Bookmarks
draditya
area of each triangle=1/2 * x * (x-4)=240..
x(x-4)=240*2=480
Immediate observations
1) Both x and x-4 have the same property of being odd or even. Since product is even, both are even.
2) One of the two x or x-4 must be multiple of 10.
Now we have to just test numbers in which x or x-4 is a multiple of 10.
10*6 or 10*14....No
20*16=320...No
20*24=480...yes
x=24..
OR
\(x^2-4x=480.....x^2-4x-480=0....x^2-24x+20x-480=0.....(x-24)(x+20)=0\)
So x can be -20 or 24. But x has to be positive, so x=24
so perimeter = 24*4=96
C
30 Sep 2015, 10:57
Kudos
Bookmarks
Hi draditya,
This question can be solved with a standard 'math' approach or it can be solved by TESTing THE ANSWERS.
We're given a number of facts to work with:
1) We start with a SQUARE piece of cloth.
2) We cut 4 feet off of one edge (and for a rectangle)
3) That rectangle is cut diagonally to form two sails (with area of 240 ft^2 each).
We're asked for the ORIGINAL PERIMETER of the cloth.
Let's TEST Answer B: 88 feet
If...
Perimeter = 88 feet
Dimensions = 22 by 22
Rectangle dimensions = 18 x 22
Triangle area = (1/2)(18)(22) = 198 ft^2 This is TOO SMALL.
Eliminate Answers A and B.
Let's TEST Answer D: 104 feet
If....
Perimeter = 104 feet
Dimensions = 26 by 26
Rectangle dimensions = 22 x 26
Triangle area = (1/2)(22)(26) = 286 ft^2 This is TOO BIG.
Eliminate Answers D and E.
There's only one answer left...
Final Answer:
GMAT assassins aren't born, they're made,
Rich
This question can be solved with a standard 'math' approach or it can be solved by TESTing THE ANSWERS.
We're given a number of facts to work with:
1) We start with a SQUARE piece of cloth.
2) We cut 4 feet off of one edge (and for a rectangle)
3) That rectangle is cut diagonally to form two sails (with area of 240 ft^2 each).
We're asked for the ORIGINAL PERIMETER of the cloth.
Let's TEST Answer B: 88 feet
If...
Perimeter = 88 feet
Dimensions = 22 by 22
Rectangle dimensions = 18 x 22
Triangle area = (1/2)(18)(22) = 198 ft^2 This is TOO SMALL.
Eliminate Answers A and B.
Let's TEST Answer D: 104 feet
If....
Perimeter = 104 feet
Dimensions = 26 by 26
Rectangle dimensions = 22 x 26
Triangle area = (1/2)(22)(26) = 286 ft^2 This is TOO BIG.
Eliminate Answers D and E.
There's only one answer left...
Final Answer:
GMAT assassins aren't born, they're made,
Rich
