Question

A bag contains $15$ red marbles, $5$ green marbles and $10$ yellow marbles. If Alex picks up a marble at random, then find the theoretical probability that it is a green marble.

• A. $\frac{1}{2}$
  
• B. $\frac{1}{3}$
  
• C. $\frac{1}{6}$
  
• D. $1$

Answer 1

The correct option is C $\frac{1}{6}$


There are $5$ green marbles.

Total number of marbles $=15+5+10$
$=30$

The theoretical probability $\text{P(Green)}$ of picking up a green marble by Alex is:

$\text{P(Green)}=\frac{\text{Number of green marbles}}{\text{Total number of marbles}}$

$\text{P(Green)}=\frac{5}{30}$

$\text{P(Green)}=\frac{1}{6}$

The theoretical probability that Alex picks up a green marble is $\frac{1}{6}$.

Therefore, option (c.) is the correct answer.