An unbiased coin is tossed 6 times. The probability that third head appears on the sixth trial is 

Probability of getting 2 heads in the first 5 trials is

${ }^5{\mathrm{C}}_2{\left(\frac{1}{2}\right)}^2{\left(\frac{1}{2}\right)}^3=\frac{10}{32}=\frac{5}{16}$

Therefore, the probability that third head appears on the sixth trial is 5/16 x 1/2 = 5/32.