A ticket ending in a given digit — Aptitude Question
A ticket ending in a given digit: Tickets numbered 1 to 40 are placed in a box and one is drawn. Answer and worked solution on CodeKairo.
- Topic: Probability
- Section: Quantitative Aptitude
- Difficulty: Easy
- Time target: 45 seconds
Question
Tickets numbered 1 to 40 are placed in a box and one is drawn. What is the probability that it is a multiple of 4?
Options
- 1/8
- 1/5
- 1/4
- 3/10
Show the answer and the worked solution
Correct answer: C. 1/4
Worked solution
- Multiples of 4 from 1 to 40: 10 numbers.
- Probability = 10/40 = 1/4.
Answer: 1/4.
The idea
Count with ⌊n/d⌋ rather than listing. Here ⌊40/4⌋ = 10 immediately.
Shortcut. Every fourth ticket is a multiple of 4, and 40 is itself one, so the fraction is exactly 1/4.
Common trap. "1/5" — the most tempting slip: counting multiples of 5 (8 of 40) by misreading the divisor.