Question
An urn contains 5 white, 6 red and 4 blue balls. Three balls are drawn at random. What is the probability that a white ball, a red ball and a blue ball are drawn?
NDA
Mathematics
Probability
2025
NDA 2025 (Phase 2)
NDA Mathematics Question (2025) — Solution
Options
- A. 28/91
- B. 2/7
- C. 24/91
- D. 23/91
Answer
C. 24/91
Step-by-step solution
Total number of balls in the urn = 5 + 6 + 4 = 15 Total number of ways to draw 3 balls from 15 balls = ^ 15 C_ 3 = 15 14 13 3 2 1 = 455 Number of ways to draw 1 white, 1 red and 1 blue ball = ^ 5 C_ 1 ^ 6 C_ 1 ^ 4 C_ 1 = 5 6 4 = 120 Required probability = 120 455 = 24 91
Related: Mathematics — Probability · All PYQ Banks