Multiple choice

A box contain 5 Red, 4 Blue and 6 Green balls, 3 balls pick randomly from the box. Find the probability that all the three balls are not of same colour?

  1. 421/ 455

  2. 34 / 455

  3. 34 / 421

  4. 23 / 421

  5. 432 / 455

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

P(all three same color) = [C(5,3)+C(4,3)+C(6,3)]/C(15,3) = (10+4+20)/455 = 34/455. P(not all same) = 1 - 34/455 = 421/455.