问一道题：NO.PZ201512300100001107 第7小题 [ CFA II ]

B.

harmonic mean.

C.

arithmetic mean.

解释：

B is correct.

The harmonic mean is sometimes used to reduce the impact of large outliers ——which are typically the major concern in using the arithmetic mean multiple—— but not the impact of small outliers (i.e., those close to zero). The harmonic mean may aggravate the impact of small outliers, but such outliers are bounded by zero on the downside.