Question:
Three unbiased coins are tossed once. Find the probability of getting exactly 2 tails
Solution:
We know that,
Probability of occurrence of an event
$=\frac{\text { Total no.of Desired outcomes }}{\text { Total no.of outcomes }}$
Let T be tails and H be heads
Total possible outcomes = TTT, TTH, THT, HTT, THH, HTH, HHT, HHH
Desired outcomes are exactly two tails. So, desired outputs are TTH, THT, HTT
Total no.of outcomes are 8 and desired outcomes are 3
Therefore, the probability of getting exactly 2 tails $=\frac{3}{8}$
Conclusion: Probability of getting exactly two tails is $\frac{3}{8}$