You agree with the first part, that the speed of sound depends on the medium. You disagree with the second part because you know that the frequency of sound does not depend on the medium.
Work Step by Step
Sound travels 4 times faster in water than in air, and travels roughly 15 times faster in steel than in air. The wave speed does depend on the medium. The frequency of the sound wave is the same as the frequency of the vibrating source that starts the sound wave. The frequency does not depend on the medium. Both of these ideas are stated on page 376.