Question 1071497
Sample space is {HHH,HHT,HTH,THH,TTH,THT,HTT,TTT}
Probability of 2 heads is 3/8
This is a binomial, and it is 1===3===3===1 for 3 heads, 2 head, 1 head, 0 heads. There are 8 possibilities, and 1 is all heads, 3 for 2 heads, 3 for 1 head, and 1 for all tails.