GMAT question - If x = 1/21 + ... - Review

Type: Problem Solving

Difficulty: 4 star rating

If mathematical expression then which of the following inequalities is true?

  1. mathematical expression
  2. mathematical expression
  3. mathematical expression
  4. mathematical expression
  5. mathematical expression

Explanation

Find an upper bound

Every fraction in the sum is less than 1/20.

So by replacing each fraction in the sum with 1/20 we can say that

mathematical expression

Therefore x is less than 1/4.

Find a lower bound

Every fraction in the sum is greater than or equal to 1/25.

So by replacing each fraction in the sum with 1/25 we can say that

mathematical expression

Therefore x is greater than or equal to 1/5

.

Put it all together

We have found that x is less than 1/4 and greater than or equal to 1/5, this matches answer C which must be correct.

Comments (3):

  1. Good One

    Anonymous on 12 Mar 2007 (permalink)

  2. Pls send me more inequilties question.thanx.

    saurabhsachdeva9 on 29 Aug 2007 (permalink)

  3. Nice

    howudoin on 4 Oct 2008 (permalink)

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