Aptitude and Engineering Ethics: Shortcuts and Professional Obligations
Aptitude: reliable shortcuts
- Successive percentage changes a% and b% give a + b + ab/100.
- Convert km/h to m/s by multiplying by 5/18; for a train crossing a platform, add train length to platform length.
- When one value in a set is replaced, the average changes by the difference divided by the count.
- Mixture problems are fastest by alligation rather than algebra.
- Permutations of n distinct objects = n!; combinations ignore order; probability = favourable outcomes/sample space.
- Data interpretation rewards approximation: round to one significant figure before computing.
Worked example
A 150 m train at 54 km/h crosses a 300 m platform. Speed = 54 × 5/18 = 15 m/s. Total distance = 150 + 300 = 450 m. Time = 450/15 = 30 s. Omitting the train's own length gives 20 s, which is usually offered as a distractor option.
Engineering ethics
- Public safety, health and welfare take precedence over loyalty to employer or client.
- Give credit for others' work; never fabricate, falsify or plagiarise data.
- Disclose conflicts of interest and refuse gifts that could sway technical judgement.
- Whistleblowing is justified when internal channels fail and a serious public threat exists.
- Sign only work you are competent to verify; keep confidential information confidential unless disclosure is legally required.
Traps
- Applying the successive-change shortcut with the wrong sign for a decrease.
- Mixing combinations and permutations in arrangement questions.
- Treating an employer's instruction as a defence for an unsafe design.
- Choosing the merely legal option where the question asks for the ethical one.