2015 AMC 10A Problem 9

Let $r_1$ and $h_1$ be the radius and height of the first cylinder and similarly define $r_2$ and $h_2$ for the second cylinder. We know that $$r_2 = \dfrac{11}{10}r_1$$ and $$\pi r_1^2h_1 = \pi r_2^2h_2.$$ Substituting and simplifying gives us $$r_1^2h_1 = \dfrac{121}{100}r_1^2h_2,$$ which tells us that $$h_1 = \dfrac{121}{100}h_2.$$ Thus, D is the correct answer.