In which situation can an average result be misleading?

Correct answer: When one extreme unusual value exists and its cause has not been checked

The direct answer is B: an average can be misleading when one extreme unusual value exists and its cause has not been checked. An average is found by adding all values and dividing by the number of values, but an extreme value can pull the result upward or downward. For example, measurements of 10, 11, 10 and 49 have an average of 20, although most observations are close to 10 or 11. Therefore the average alone may not represent the usual result. Option B is correct because the unusual value needs investigation before the average is interpreted; it may be a mistake or a genuine variation. Option A is wrong because similar measurements usually give a representative average. Option C is wrong because using the same unit improves, rather than harms, comparison. Option D is wrong because repetition generally provides more evidence, although it still must be done carefully. Memory cue: inspect extreme values before trusting an average.