[译] 那种新型火车速度超过平均速度3.5倍。
[误] The speed of the new-type train exceeds the average speed by a factor of 3.5.

[正] The speed of the new-type train exceeds the average speed by a factor of 4.5.
[注] 在 increase by a factor of 句型中，译成汉语时须减少 1 倍。又如：The productivity has been increased by a factor of 2.5 in that plant. 该厂生产率增长 1.5 倍。