From: Lee Corbin (email@example.com)
Date: Sat Jul 05 2003 - 23:06:16 MDT
Has anyone got more hard problems using Bayes' Theorem?
The ones in my textbooks aren't that challenging, e.g.,
#2 below. It was here on this list that the following
great problems were posted.
1. It is known that about 1 woman in 100 gets breast cancer.
When a woman does have breast cancer, the test detects it
80 percent of the time. About one time in ten, however,
the test creates a false-positive; that is, someone who
does not have breast cancer nonetheless gets a positive
reading from the test. Given that a particular woman has
just scored positive on the test, what is the actual
probability that she has breast cancer?
2. If there is a burglary on a particular night the probability
is .99 that the burglar alarm will ring. If there is no
burglary on a particular night the probability is .005 that
the burglar alarm will ring, falsely. The probability is
.001 that a burglary will occur on a particular night.
What is the probability that there is a burglary, given
that the alarm just rang?
3. The probability that a newborn will have deformities
traceable to a sickness of its mother during pregnancy is 1%.
If a child is born healthy and normal, the probability that
the mother had rubella during her pregnancy is 10%. If a
child is born with deformities and it can be traced to some
sickness of the mother, the probability that the mother had
rubella during her pregnancy is 50%. What is the probability
that a child will be born with deformities if its mother had
rubella during her pregnancy?
4. (and Eliezer's egg problem, which I don't have ready to hand).
5. A nurse has just started to count the babies in a hospital
nursery. She has just counted that there are two boys, and has
not counted the girls, when, at 11:00, a new baby is brought
in to the nursery. A baby is then selected at random, from
all the babies present, to have its footprint taken. The
selected baby happens to be a boy. What is the probability
that the baby added at 11:00 was a girl?
This archive was generated by hypermail 2.1.5 : Sat Jul 05 2003 - 23:15:18 MDT