When 3 fair coins are tossed, the probability of exactly one head appearing is found from: [tex]P(1\ head)=3C1\times(\frac{1}{2})^{3}=\frac{3}{8}[/tex] Therefore in 100,000 trials we would expect to see exactly one head [tex]100,000\times\frac{3}{8}=37,500\ times[/tex]
