The description of the relationship between study time and test scores, where doubling study time generally leads to an increase in test scores, suggests an exponential function. Exponential functions have the form \(f(x) = a \cdot b^x\), where \(a\) and \(b\) are constants.
In this case, since doubling study time results in an increase in test scores, it aligns with the behavior of exponential growth. Therefore, an exponential growth function \(f(x) = a \cdot 2^x\) could be a suitable model for test scores as a function of time studied.