GMAT question - A circular archery target contains a circular bu... - Review

Type: Data Sufficiency

Difficulty: 3 star rating

Two concentric circles

A circular archery target contains a circular bull's eye, shaded grey in the diagram above. If an arrow is equally likely to hit any point on the archery target what is the probability that the point at which it hits the target is within the bulls eye?

  1. The archery target has a radius of 75cm
  2. The radius of the bull's eye is one fifth the radius of the archery target
  1. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient
  2. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient
  3. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient
  4. EACH statement ALONE is sufficient
  5. Statements (1) and (2) TOGETHER are NOT sufficient

Explanation

Simplify the question

The probability that the arrow hits within the bull's eye is equal to ratio between the area of the bull's eye and the area of the whole target.

So to answer this question we need to be able to work out this area.

Is statement (1) sufficient?

Statement (1) tells us what the radius (and therefore the area) of the archery target BUT tells us nothing about the area of the bull's eye and so is NOT sufficient to answer the question.

Is statement (2) sufficient?

Statement (2) tells us what the ratio between the radii of the archery target and the bull's eye is. From this we could work out what the ratio between the area's is. Therefore statement (2) is sufficient to answer the question.

Select an answer

Since statement (2) in its own sufficient to answer the question the correct answer is B.

Comments (2):

  1. i like it..

    mkb on 22 Nov 2009 (permalink)
  2. Good method for solving the data questions.From Apurva.

    bsnl2009 on 6 Feb 2010 (permalink)

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