If you were to toss four coins, what are the odds in favor of at least two landing heads up?
What is the sample space of four coins being tossed:
HHHH, HHHT, HHTH, HTHH, THHH. . .etc. Now of those how many have at least two H's in them?
Or, if you have studied the binomial formula, you recognize this as a binomial distribution with four independent trials (the individual coins being tossed).