age

A common GMAT word problem involves calculating the age of two or more people. This can be easily solved using our standard word problem approach.  Simply assign variables and then translate the problem statement into mathematical expressions that can be easily manipulated.

Example

Sid is twice as old as Rex. Ten years ago, Sid was four times as old as Rex. How old is Sid today?

Solution

  1. The question is asking for Sid’s age.
  2. The two unknowns in this problem are Sid and Rex’s age. Since the first sentence already gives us a relation between Sid and Rex, we can use one variable to represent both of them.

    3. Let x = Rex’s age
    2x = Sid’s age

  3. The below expression essentially states that 10 years ago, Sid was 4 times older than Rex

    4. example1

  4. Solve.

    5. example2

    Rex is 15 years old, so Sid is 30 years old. The answer is 30.


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