Question

In a box, there are 3 red pens, 2 green pens and 1 blue pen. Johan picks a pen blindfoldly. The probability of picking a red pen or a green pen is .

• A. $\frac{1}{2}$
• B. $\frac{1}{3}$
• C. $\frac{5}{6}$

Answer 1

The correct option is C $\frac{5}{6}$

In the pen box,
$\bullet$ number of red pens= $3$
$\bullet$ number of green pens= $2$
$\bullet$ number of blue pen= $1$
$\therefore$ Total number of pens in the box= $3+2+1=6$

Now,
$\text{P(picking a red pen)}=\frac{\text{Number of red pens}}{\text{Total number of pens}}$

$\Rightarrow \text{P(picking a red pen)}=\frac{3}{6}$

Next,
$\text{P(picking a green pen)}=\frac{\text{Number of green pens}}{\text{Total number of pens}}$

$\Rightarrow \text{P(picking a green pen)}=\frac{2}{6}$

$\text{Need to find:}$ Probability of picking a red pen or a green pen

$\text{P(picking a red pen or a green pen) = P(picking a red pen) + P(picking a green pen)}$

$\Rightarrow \text{P(picking a red pen or a green pen)}=\frac{3}{6}+\frac{2}{6}$

$\Rightarrow \text{P(picking a red pen or a green pen)}=\frac{3+2}{6}=\frac{5}{6}$

$\therefore$ The probability of picking a red pen or a green pen is $\frac{5}{6}$.