Observations of the “traffic” on a data structure over a certain period of time indicate that 500 Insert operations, 500 Delete operations, 700 Fetch operations, and 200 Update operations were performed on a data set. If Insert operations take 10 nanoseconds, Delete operations take 250 nanoseconds, Fetch operations 200 nanoseconds, and Update operations take 300 nanoseconds, determine:

(a)  the probability of performing a Fetch operation over the observation period.

(b)  the average speed, in nanoseconds, of the data structure over the observation period.