The cost per household for taking the U.S. census has increased exponentially since 1970 (Source: GAO analysis

Question:

The cost per household for taking the U.S. census has increased exponentially since 1970 (Source: GAO analysis of U.S. Census Bureau data). The following function models the increase in cost:
C(x) = 15.5202(1.0508)x,
Where x is the number of years since 1970 Estimate the cost per household in 1990 and in 2010