Total from those present — Percentages Aptitude Question
Total from those present: In a class 20% of the students were absent and 32 were present. Answer and worked solution on CodeKairo.
- Topic: Percentages
- Section: Quantitative Aptitude
- Difficulty: Easy
- Time target: 40 seconds
Question
In a class 20% of the students were absent and 32 were present. What is the total strength of the class?
Options
- 36
- 40
- 42
- 45
Show the answer and the worked solution
Correct answer: B. 40
Worked solution
- Present = 80% of total = 32.
- Total = 32 ÷ 0.80 = 40.
Answer: 40.
The idea
Convert the stated percentage into the one you were given a number for, then divide. Adding 20% to 32 gives 38.4 and is wrong, because the 20% is of the total, not of those present.
Shortcut. 32 present is 80% = 4/5 of the class, so one fifth is 8 and the class is 5 × 8 = 40.
Common trap. 36 — adding a few absentees to 32 by eye looks reasonable, but 80% of 36 is 28.8, not 32; a full fifth of the class (8) must be absent.