Solutions - 5020-04

(1) Describe the sample space:

$$\mathrm{\Omega }={\{H,T\}}^3\gg \gg |\mathrm{\Omega }|=2^3=8$$

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(2) Count favorable outcomes and compute probability:

The sequences with at least two heads are $\{HHT,HTH,THH,HHH\}$, giving $4$ favorable outcomes.

$$P[\text{at least two heads}]=\frac{4}{8}=\frac{1}{2}$$