CS 3001 MIDTERM EXAM 2025
QUESTIONS AND ANSWERS
What hapened with the Therac-25? - ANS There was a malfunction with the software due to
many casual factors which led to multiple accidents which also led to 3 deaths between 1985-
1987. There were 11 installed machines and 6 accidents. FDA did not have any formalized
procedures at the time and the company creating the machines, AECL, were Canadian. For
every accident, there are an estimated 600 close calls/minor incidents. Low reporting bc of peer
pressure, fear of regulatory bodies, and fear of lawsuits.
What are the differences between the Therac-20 and 25? - ANS 20 had built in hardware
checks which contained the possibility of overdosing but the 25 relied solely on software which
was integrated with the machine and led to overdoses.
What was the cooporate response to the Therac-25? - ANS AECL repeatedly said "that's not
possible" when told of errors. Falsely said they increased safety by 5 orders of magnitude. A
better response would include warning users, and recreating the error to understand the
problem. When radian machines are taken out the market, life changing treatment is not as
accessible.
What are the casual factors for the therac-25? (10 things) - ANS 1. Overconfidence in
software
2. Confusing reliability with safety
3. Lack of Defensive Design
4. Failure to eliminate root causes
5. Unrealistic risk assessments
6. Inadequate investigation or follow-up on accident reports
1 @COPYRIGHT THEBRIGHT 2025/2026
, 7. Inadequate software engineering practices
8. Software reuse
9. Safe versus friendly user interfaces
10. User and government oversight and standards
Examples of artifacts with intentional politics? - ANS Bridges in NYC are built intended to
keep poor people away from beaches because public buses are not able to go there. We know
it was intentional bc the designer was racist and said racist things.
Example of artifacts with unintentional politics? - ANS Stairs were not intended to exclude
people in wheelchairs. Another example is the tomato harvester. It saves money but gives
advantage to big farms and tougher tomatoes are made.
Example of something that is not wrong, but harmful. Example of something is is wrong, not
harmful - ANS For first, taking a job that someone else needed it more.
For second, white hat hacking: hacking into OS to tell developers about an error.
Relativism
Cultural relativism - ANS You are a passenger and your friend speeds and get into an
accident. Depending on what culture the people were, they would rat them out. Saying it is
relative does not explain anything due to cultural differences.
Explain both types of Utilitarianism - ANS Act U: Performs analysis on each act and how
much utility/happiness it generates for affected parties.
Problems:
-does not account for innate sense of duty. It says breaking promise is okay if it generates for
happiness.
-morality has nothing to with intent.
-no absolute right. i.e. okay killing someone to give 10 ppl organs.
2 @COPYRIGHT THEBRIGHT 2025/2026
QUESTIONS AND ANSWERS
What hapened with the Therac-25? - ANS There was a malfunction with the software due to
many casual factors which led to multiple accidents which also led to 3 deaths between 1985-
1987. There were 11 installed machines and 6 accidents. FDA did not have any formalized
procedures at the time and the company creating the machines, AECL, were Canadian. For
every accident, there are an estimated 600 close calls/minor incidents. Low reporting bc of peer
pressure, fear of regulatory bodies, and fear of lawsuits.
What are the differences between the Therac-20 and 25? - ANS 20 had built in hardware
checks which contained the possibility of overdosing but the 25 relied solely on software which
was integrated with the machine and led to overdoses.
What was the cooporate response to the Therac-25? - ANS AECL repeatedly said "that's not
possible" when told of errors. Falsely said they increased safety by 5 orders of magnitude. A
better response would include warning users, and recreating the error to understand the
problem. When radian machines are taken out the market, life changing treatment is not as
accessible.
What are the casual factors for the therac-25? (10 things) - ANS 1. Overconfidence in
software
2. Confusing reliability with safety
3. Lack of Defensive Design
4. Failure to eliminate root causes
5. Unrealistic risk assessments
6. Inadequate investigation or follow-up on accident reports
1 @COPYRIGHT THEBRIGHT 2025/2026
, 7. Inadequate software engineering practices
8. Software reuse
9. Safe versus friendly user interfaces
10. User and government oversight and standards
Examples of artifacts with intentional politics? - ANS Bridges in NYC are built intended to
keep poor people away from beaches because public buses are not able to go there. We know
it was intentional bc the designer was racist and said racist things.
Example of artifacts with unintentional politics? - ANS Stairs were not intended to exclude
people in wheelchairs. Another example is the tomato harvester. It saves money but gives
advantage to big farms and tougher tomatoes are made.
Example of something that is not wrong, but harmful. Example of something is is wrong, not
harmful - ANS For first, taking a job that someone else needed it more.
For second, white hat hacking: hacking into OS to tell developers about an error.
Relativism
Cultural relativism - ANS You are a passenger and your friend speeds and get into an
accident. Depending on what culture the people were, they would rat them out. Saying it is
relative does not explain anything due to cultural differences.
Explain both types of Utilitarianism - ANS Act U: Performs analysis on each act and how
much utility/happiness it generates for affected parties.
Problems:
-does not account for innate sense of duty. It says breaking promise is okay if it generates for
happiness.
-morality has nothing to with intent.
-no absolute right. i.e. okay killing someone to give 10 ppl organs.
2 @COPYRIGHT THEBRIGHT 2025/2026
