### Three unbiased coins are tossed simultaneously. Find the probability of getting exactly $2$ heads.

$\dfrac { 3 } { 8 }$

Step by Step Explanation:
1. When $3$ coins are tossed simultaneously, all the possible outcomes are $HHH, HHT, HTH, THH, HTT, THT, TTH,$ and $TTT.$

So, total number of possible outcomes = $8$.
2. Let $E$ be the event of getting exactly $2$ heads.

The favourable outcomes are $HHT, HTH,$ and $THH.$

Number of favouable outcomes = $3$ \begin{aligned} \therefore \space P(\text{ getting exactly 2 heads }) = P(E) = \dfrac { \text { Number of favourable outcomes } } { \text { Total number of outcomes } } = \dfrac { 3 } { 8 }. \end{aligned} Thus, the probability of getting exactly $2$ heads = $\dfrac { 3 } { 8 }$