Question:
A die is tossed thrice. Find the probability of getting an odd number at least once.
Solution:
Probability of getting an odd number in a single throw of a die $=\frac{3}{6}=\frac{1}{2}$
Similarly, probability of getting an even number $=\frac{3}{6}=\frac{1}{2}$
Probability of getting an even number three times $=\frac{1}{2} \times \frac{1}{2} \times \frac{1}{2}=\frac{1}{8}$
Therefore, probability of getting an odd number at least once
$=1$ - Probability of getting an odd number in none of the throws
$=1$ - Probability of getting an even number thrice
$=1-\frac{1}{8}$
$=\frac{7}{8}$