A survey of cars on a certain stretch of highway during morning commute hours showed that 70%

Question:

A survey of cars on a certain stretch of highway during morning commute hours showed that 70% had only one occupant, 15% had 2, 10% had 3, 3% had 4, and 2% had 5. Let X represents the number of occupants in a randomly chosen car.
a. Find the probability mass function of X.
b. Find P(X ≤ 2).
c. Find P(X > 3).
d. Find μX .
e. Find σX .