GMAT question - The square ABCD has sides of length 4. Point E is ha... - Review

Type: Problem Solving

Difficulty: 4 star rating

The square ABCD has sides of length 4. Point E is half way between A and D, point F is half way between B and C and point G is half way between E and F. What is the area enclosed by the polygon ABCDEG?
  1. 16
  2. 14
  3. 12
  4. 10
  5. 8

Explanation

The key to this question will be keeping track of all the information we are provided with.

Draw diagrams

We can do this by drawing diagrams on your note board.

From the question we have,

"The square ABCD has sides of length 4."
Diagram of square ABCD with sides length 4

And then,

"Point E is half way between A and D, point F is half way between B and C and point G is half way between E and F."
Diagram of square ABCD with sides length 4 and points E, F and G added

And finally,

What is the area enclosed by the polygon ABCDEG?
Diagram showing shaded area ABCDEG

Work out the area

You can see that the area of the shaded region ABCDEG is equal to the area of square ABCD minus the area of triangle AEG.

mathematical expression

The area of the polygon ABCDEG is 14 and the correct answer is B.

Comments (4):

  1. This is a terrible explanation.

    Just do 16 minus the area of the missing triangle.

    16 - [1/2 b*h] of the missing triangle

    16 - [1/2 (2*2)]

    = 14

    booky28 on 26 Jan 2009 (permalink)
  2. I agree, it is clearer if you treat this as the area of the square minus the triangle that has been removed. I have updated the explanation to reflect this.

    joel on 27 Jan 2009 (permalink)
  3. But for those who have a little knowledge, it will be very useful

    ilaila on 4 Feb 2009 (permalink)
  4. This is a stupid question. No where does it say that point E has to be on the line AD. Point E could be internal to the square and still be halfway from both A and D.

    misterchipper on 22 Mar 2010 (permalink)

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