Delegates at a conference — Caselets Aptitude Question
Delegates at a conference: A conference had 800 delegates. 45% attended the morning session and 60% the afternoon… Answer and worked solution on CodeKairo.
- Topic: Caselets
- Section: Data Interpretation
- Difficulty: Hard
- Time target: 90 seconds
Question
A conference had 800 delegates. 45% attended the morning session and 60% the afternoon session, while 25% attended both.
How many attended neither session?
Options
- 120
- 140
- 160
- 180
Show the answer and the worked solution
Correct answer: C. 160
Worked solution
- At least one session = 45 + 60 − 25 = 80% of delegates.
- Neither = 20% of 800 = 160.
Answer: 160.
The idea
Work in percentages until the final step, then convert once. Subtracting the overlap is what keeps the union below 100%.
Shortcut. Neither = both − (A + B − 100): the two sessions sum to 105%, overshooting by 5, so neither = 25 − 5 = 20% of 800 = 160.
Common trap. 120 — subtracting only the afternoon 60% and the 25% overlap from 100% (15%), forgetting the 20% who attended the morning alone.