Math Help - probability distributions

1. probability distributions

A coin is tossed 8 times. Calculate the probability of tossing
a) 6 heads and 2 tails
b) 7 heads and 1 tail

2. Originally Posted by shell
A coin is tossed 8 times. Calculate the probability of tossing
a) 6 heads and 2 tails
b) 7 heads and 1 tail
c. $\sum\limits_{k = 6}^8 {\binom{8}{k}\left( {0.5} \right)^8 }$