1. Sophie is a dog that loves to play catch. Unfortu- nately, she isn't very good, and the probability that she catches a ball is only .1. Let x be the number of tosses required until Sophie catches a ball.
a. Does x have a binomial or a geometric distribution?
b. What is the probability that it will take exactly two tosses for Sophie to catch a ball?
c. What is the probability that more than three tosses will be required?
2. Suppose that 20% of the 10,000 signatures on a certain recall petition are invalid. Would the number of invalid signatures in a sample of 2000 of these signatures have (approximately) a binomial distribution? Explain.