# From a bag containing 10 red, 4 blue and 6 black balls, a ball is drawn at random. Find the probability of drawing a blue or black ball - Mathematics and Statistics

Sum

From a bag containing 10 red, 4 blue and 6 black balls, a ball is drawn at random. Find the probability of drawing a blue or black ball

#### Solution

The bag contains 10 red, 4 blue and 6 black balls, i.e., 10 + 4 + 6 = 20 balls.

One ball can be drawn from 20 balls in 20C1 ways.

∴ n(S) = 20C1 = 20

Let event B: The ball drawn is blue or black.

There are 4 blue and 6 black balls.

∴ 1 blue ball can be drawn from 4 blue balls in 4C1 ways or 1 black ball can be drawn from 6 black balls in 6C1 ways.

∴ n(B) = 4C1 + 6C1 = 4 + 6 = 10

∴ P(B) = ("n"("B"))/("n"("S"))

= 10/20

= 1/2.

Concept: Basic Terminologies
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