Question

A bag contains 5 black balls, 4 white balls and 3 red balls. If a ball is selected randomwise, the probability that it is black or red ball is

Options

•  1/3

• 1/4

•  5/12

•  2/3

   

Answer 1

2/3

Out of 12 balls, one ball can be drawn in ¹²C₁ ways.
∴  Total number of elementary events = ¹²C₁ = 12
Out of fivne black balls, one black ball can be chosen in ⁵C₁ = 5 ways.
Out of three red balls, one red ball can be chosen in ³C₁ = 3 ways.
∴ Favourable number of events = 5 + 3 = 8
Hence, required probability = \[\frac{8}{12} = \frac{2}{3}\]