any help would be greatly appreciated

A student wants to go to the gym, but it hard to find time between work and classes. Through observation, student has established a probability distribution of a time he will be able to attend gym during the week. X P (x ) 2 0.4 3 0.3 4 0.2 5 0.1 a. What is the lowest limit of a probability function? b. On average, how many hours the student will be able to go to the gym per week