Question

The average time betweenarrivals of two cars at traffic lights is 0.25 minutes

a) Determine the probability that the time between two car arrivals will be less than 30 seconds

b) What is the probability that exactly 2 cars will go through the traffic lights in one minute?

Answer 1

a)

Let X denote the inter-arrival time between 2 cars at traffic light (in minutes). Then

So,

Required probability =

b)

Let Y denote the number of cars going through traffic in one minute. Then

Required probability =