Activity 1 has an optimistic eestimate of 7 days, a most likely estimate of 16 days and a pessimistic estimate of 25 days. What is the approximate calculated probability that the activity will be finished in 10 to 22 days?

A. 95.4%

B. 50.0%

C. 99.7%

D. 68.3%

How to arrive at the correct answer? Appreciate if any of you can help me on this.