Which average is affected most by the presence of extreme items?

arithmetic mean

The correct answer is option 3: arithmetic mean

Arithmetic mean is affected by extreme values. Any large value, on either end, can push it up or down.

The arithmetic mean (or simply the mean) is highly sensitive to extreme values (outliers) because it considers every data point in the calculation. Outliers can significantly skew the mean, making it unrepresentative of the central tendency of the dataset.

In contrast, the median and mode are more robust to outliers. The median, being the middle value, is less influenced by extreme values at either end, and the mode, being the most frequent value, is unaffected by individual extreme values.