Help! If I roll a die 8 times...I'd like to know the probability of getting an odd number.

a) exactly 3 times.

b) at least 7 times.

c) at most 6 times.

using the formula: nCr (p)^r (1-p)^n-r (I couln't figure out how to superscript the appropriate letters. I'm hoping whoever can help me out will know what I'm talking about)