Answer:
See below in bold.
Step-by-step explanation:
For the fair coin Prob(head) = 1/2 and Prob(Tail) = 1/2.
For the biased coin it is Prob(head) = 2/3 and Prob(Tail) = 1/3.
a) Prob(2 heads) = 1/2 * 2/3 = 1/3.
b) Prob(2 tails) = 1/2 * 1/3 = 1/6.
c) Prob(1 head ) = Prob(H T or T H) = 1/2 * 1/3 + 1/2 * 2/3) = 1/6+1/3 = 1/2.
d) Prob (at least one head) = prob (HH or TH or HT) = 1/3 + 1/2 = 5/6.