Question

a driver passes 4 sets of traffic lights. the random varaible X is the number of traffic lights he has to stop at. the probabilty distribution for x is given:

x 0 1 2 3 4
prob 0.1 0.2 0.3 0.2 0.2

a) find the upper quartile of the number of traffic lights at which the driver has to stop for on a single trip ?

b) The total travel time (T) is the driving time plus the waiting time at traffic lights. The driving time for the trip is 13 minutes and the waiting time at each set of lights the driver has to stop at is 2 minutes. Give an equation relating the total travel time to the
driving time and the number of traffic lights stopped at ?

c) What is the probability that the total trip time is less than 18 minutes?

d) What is the probability that the total trip time is less than 18 minutes?

take a shot. what do you think are the answers?