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QUANTITATIVE REASONING · GMAT-Q-NL-01

Number Line, Intervals and Comparisons

GMAT lesson development preview · DRAFT · Original learning and assessment material

Concepts and problem-solving strategy

Order on a number line

Interval intersection

Distance between points

Think Like a GMAT Test-Taker

Mark open and closed endpoints and translate intervals to inequalities.

Faster Methods

Use interval intersection to combine simultaneous inequalities.

Compare distance via subtraction or absolute value.

Keep strict and non-strict endpoint symbols distinct.

Worked example 1

Describe the intersection of -2<x<5 and x≥1.

The left endpoint 1 is included; 5 is not.

Worked example 2

Find the distance between -7 and 4.

Subtract endpoints and take absolute value.

Common Traps

  • Multiplying an inequality by a negative reverses its direction.
  • An open endpoint is excluded.
  • Distance is nonnegative regardless of the order of subtraction.
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