I'm taking a course in probability and statistics and encountered an exercise with a formulation that doesn't make sense at all to my English-as-second-language ears. I will recite the exercise here and maybe you could help my settle wether if the original formulation is bad, or if I've found an opportunity to learn a new way of formulating myself in English. The exercise is from "Introduction to Probability and Statistics" by J.Susan Milton and Jesse C. Arnold (McGraw-Hill 2004). I'll quote some excerpts that I think will provide enough information. Section 3.4, ex. 25: The density function is given by f(x) = (1-p)x-1*p (geometric) where p=.05 Now (e) doesn't make any sense at all to me. What makes least sense is the use of "that". It's solved by P(X≥3) = 1-( f(1) + f(2) ) However, a more appropriate formulation of (e) I then think would be for instance: What do you think? Is the original formulation of (e) good, quite inprecise or even incorrect?