Given the following data:
Determine, if possible, the conditional probability
% file npr03_01.m
% Data for Exercise 1
minvec3
DV = [A|Ac; A; A&B; B&C; Ac|(B&C); Ac&B&Cc];
DP = [ 1 0.55 0.30 0.20 0.55 0.15 ];
TV = [Ac&B; B];
disp('Call for mincalc')
npr03_01
Variables are A, B, C, Ac, Bc, Cc
They may be renamed, if desired.
Call for mincalc
mincalc
Data vectors are linearly independent
Computable target probabilities
1.0000 0.2500
2.0000 0.5500
The number of minterms is 8
The number of available minterms is 4
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P = 0.25/0.55
P = 0.4545
In Exercise 11 from "Problems on Minterm Analysis," we have the following data: A survey of a represenative group of students yields the following information:
Let A = male, B = on campus, C = active in sports.
npr02_11
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mincalc
- - - - - - - - - - - -
mincalct
Enter matrix of target Boolean combinations [A&B&C; A&B; Ac&B&C; C]
Computable target probabilities
1.0000 0.3200
2.0000 0.4400
3.0000 0.2300
4.0000 0.6100
PC_AB = 0.32/0.44
PC_AB = 0.7273
PAcB_C = 0.23/0.61
PAcB_C = 0.3770
In a certain population, the probability a woman lives to at least
seventy years is 0.70 and is 0.55 that she will live to at least eighty years.
If a woman is seventy years old, what is the conditional probability she will
survive to eighty years? Note that if
Let
From 100 cards numbered 00, 01, 02,
B0 is the event one of the first ten is drawn.
Two fair dice are rolled.
Four persons are to be selected from a group of 12 people, 7 of whom are women.
Twenty percent of the paintings in a gallery are not originals. A collector buys a painting. He has probability 0.10 of buying a fake for an original but never rejects an original as a fake, What is the (conditional) probability the painting he purchases is an original?
Let
Five percent of the units of a certain type of equipment brought in for service have a common defect. Experience shows that 93 percent of the units with this defect exhibit a certain behavioral characteristic, while only two percent of the units which do not have this defect exhibit that characteristic. A unit is examined and found to have the characteristic symptom. What is the conditional probability that the unit has the defect, given this behavior?
Let
A shipment of 1000 electronic units is received. There is an equally likely probability that there are 0, 1, 2, or 3 defective units in the lot. If one is selected at random and found to be good, what is the probability of no defective units in the lot?
Let
Data on incomes and salary ranges for a certain population are analyzed
as follows.
| S1 | S2 | S3 | |
| E1 | 0.85 | 0.10 | 0.05 |
| E2 | 0.10 | 0.80 | 0.10 |
| E3 | 0.05 | 0.50 | 0.45 |
|
|
0.50 | 0.40 | 0.10 |
In a survey, 85 percent of the employees say they favor a certain company policy. Previous experience indicates that 20 percent of those who do not favor the policy say that they do, out of fear of reprisal. What is the probability that an employee picked at random really does favor the company policy? It is reasonable to assume that all who favor say so.
A quality control group is designing an automatic test procedure for
compact disk players coming from a production line. Experience shows that
one percent of the units produced are defective. The automatic test procedure
has probability 0.05 of giving a false positive indication and probability
0.02 of giving a false negative. That is, if D is the event a unit
tested is defective, and T is the event that it tests satisfactory,
then
Five boxes of random access memory chips have 100 units per box. They have respectively one, two, three, four, and five defective units. A box is selected at random, on an equally likely basis, and a unit is selected at random therefrom. It is defective. What are the (conditional) probabilities the unit was selected from each of the boxes?
Two percent of the units received at a warehouse are defective. A nondestructive test procedure gives two percent false positive indications and five percent false negative. Units which fail to pass the inspection are sold to a salvage firm. This firm applies a corrective procedure which does not affect any good unit and which corrects 90 percent of the defective units. A customer buys a unit from the salvage firm. It is good. What is the (conditional) probability the unit was originally defective?
Let
At a certain stage in a trial, the judge feels the odds are two to one the defendent is guilty. It is determined that the defendent is left handed. An investigator convinces the judge this is six times more likely if the defendent is guilty than if he were not. What is the likelihood, given this evidence, that the defendent is guilty?
Let
Show that if
The converse is not true. Consider
But
Since
Suppose
Use property (CP4) to show
Show that
Show that
An individual is to select from among n alternatives in an attempt to
obtain a particular one. This might be selection from answers on a
multiple choice question, when only one is correct. Let A be the
event he makes a correct selection, and B be the event he knows which
is correct before making the selection. We suppose
Polya's urn scheme for a contagious disease. An urn contains
initially b black balls and r red balls (