Between what two integers does 98 fall between

Math it's appreciated. (picture provided)

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.

Either enter an exact answer in terms of \piπ or use 3.143.14 for \piπ and enter your answer as a decimal.