The end of task 2, just above the definition of the SD above Task 3, starts talking about being interested in the mothers' ages, then suddenly cuts mid-sentence to discussing the heights, which actually happens in Task 4 :) I think it should continue talking about the ages here. This sentence:
"We are also interested in the standard deviation of mother’s ages. The SD gives us a sense of how variable mothers' ages are around the average mothers' -->age<--. If the SD is large, then the mothers' --->heights<--- should spread over a large range from the mean. If the SD is small, then the mothers' --->heights<--- should be tightly clustered around the average mother ---->height<---."
@mujisashi mentioned: