Amy and three friends launch a new website. each of the four friends e-mails the web address to three new friends. these new friends forward the web address to three more friends. if no one receives the e-mails more than once, how many people will receive the web address in the second wave of e-mails?

David estimated he had about 20 fish in his pond. a year later, there were about 1.5 times as many fish. the year after that, the number of fish increased by a factor of 1.5 again. the number of fish is modeled by f(x)=20(1.5)^x. create a question you could ask that could be answered only by graphing or using a logarithm.