Question

A bag contains 5 red marbles, 8 white marbles, 4 green marbles. What is the probability that if one marble is taken out of the bag at random, it will be 

not green

Answer 1

\[\text{ Number of red marbles }= 5\]
\[\text{ Number of white marbles }= 8\]
\[\text{ Number of green marbles } = 4\]
\[\text{ Total number of marbles in the bag }= 5 + 8 + 4 = 17\]
\[ \therefore \text{ Total number outcomes }= 17\]

\[\text{ Let C be the event of drawing a green ball } . \]
\[ \therefore P\left( C \right) = \frac{\text{ Number of favourable outcomes }}{\text{ Total number of outcomes }} = \frac{4}{17}\]
\[\text{ Now, the event of not drawing a green ball is }: \]
\[P\left( C \right) = 1 - P\left( C \right) = 1 - \frac{4}{17} = \frac{13}{17}\]