ACCY 302 (Chen)
Class 24
Fall 2009
Additional Study Questions
Review and Applications of Basic Statistics
1.
Parts Problems
Source:
Adapted from Anderson, Sweeney and Williams
A manufacturing firm receives shipments of parts from two different suppliers, Ace Company and Action
Company.
Currently, 65% of the parts purchased by the company are from Ace, and the remaining are from
Action.
The quality of the purchased parts varies with the source of supply.
Based on historical data, the conditional
probabilities of receiving good and bad parts are:
Good Parts
Bad Parts
Ace Company
.98
.02
Action Company
.95
.05
If a part is found to be bad, what is the probability that it came from Ace?
From Action?
2.
Prospect Fields in Oil and Gas
An oil company’s geological assessment indicates that there’s a 25% chance that a particular prospect field
will produce oil.
Further, there’s an 80% chance that a particular well will strike oil given that oil is present
in the field.
Suppose that one well is drilled on the field and it comes up dry.
What is the probability that the
prospect field will produce oil?
3.
Predicting the Weather
Suppose that you believe the chance that it will rain is 30%.
When you are watching television, the weather
person tells you that it’s going to rain tomorrow.
Suppose that you know that the weather person is pretty
good, and makes mistakes only 10% of the time.
In other words, if it’s actually going to rain tomorrow the
weather person says it’s going to rain with probability 0.9 and says it’s not going to rain with probability 0.1;
if it’s not going to rain tomorrow she says it’s going to rain with probability 0.1 and says it’s not going to rain
with probability 0.9.
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 Spring '08
 Staff
 Conditional Probability, Probability, weather, Type I and type II errors

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