The sign of a is positive. The sign of b is negative

The sign of a is positive. The sign of b is negative. If it can be determined, what is the sign of the mean of a and b ?

  1. Positive
  2. Negative
  3. Both positive and negative
  4. Neither positive nor negative
  5. Cannot be determined from the given information

Answer

The correct answer is E.

The mean of a and b is (a + b)/2. Because a is positive and b is negative, the mean is (|a| - |b|)/2.

If |a| > |b|, then the mean is positive. If |a| < |b|, then the mean is negative. If |a| = |b|, then the mean is 0. Because we only know the sign of a and b and not their magnitudes, we cannot determine if the mean is positive, negative, or 0.