The following table denotes the probability distribution for X, the number of sick days employees at a small company take off from work in a given year:

X	0	1	2	3	4	5	6	7
P(X)	0.11	0.32	?	0.00	0.35	0.00	0.00	0.13

Since there are a small number of employees, some values of X were not observed. For example, no employee had 6 sick days.

Find P(X2) and describe what this probability tells us.

Find the expected value of X and explain the meaning of this value.

Among the employees who called out sick at least once, find the probability that a selected employee had exactly one sick day.