I am doing a review and I cannot seem to figure out 2 problems that I must know for my actual classwork....

--> What is the probability of getting at least 3 tails when tossing a coin six times

(I understand that get all tails would be 1/64 but when I try to substitute the prob for getting a tails it is 1/2 and I get all confused...)

----> A bus has 7 stops and 4 passengers. Given that each passenger is equally likely to get off at any stop, What is the probability that 2 will get off at the same time.

Any help would be greatly appreciated!

Antony