Exercises on
Discrete distributions
1
A traffic control engineer reports that 75%
of the vehicles passing through a
checkpoint are from within the state. What
is the probability that fewer than 2 of the
next 5 vehicles are from out of state?
2
Suppose that a computer programmer, on
average, makes 3 errors in 500 lines of
code. What is the probability that the
programmer will make no errors in 250
lines of code?
3
Six is the average number of oil tankers
arriving each day at a certain port city.
The facilities can handle at most 10
tankers per day. What is the probability
that on a given day, some tankers will
have to be turned away?
4
An Air Force intercept squadron consists of
16 planes that should always be ready for
immediate launch. However, there is a
probability of 0.25 that the engine of each
plane will not start at a given attempt. If
this happens, the mechanics must wait 5
minutes before trying to start the engine
again. What is the expected number of
planes to immediately launch?
5
The number of cracks in a section of
interstate highway averages 2 per mile.
What is the probability that there will be at
least 1 crack in the next ½ mile of the
highway?
6
A particularly long traffic light on your way
to work in the morning is green 20% of
the time that you approach it. Over 20
mornings, what is the probability that the
light is green on exactly 4 days?
7