First, you should find:
Probability of NOT getting a tail in 3 coin toss:
[tex](\frac{1}{2})^3=\frac{1}{8}[/tex]After that, you should find the probability of getting at least one tail in 3 fair coins tossed
[tex]1-\frac{1}{8}=\frac{8-1}{8}=\frac{7}{8}[/tex]Answer: 7/8
