<span>carbon, hydrogen, and oxygen onLY</span>
The time
it takes for the key to fall 44 m is

(notice I'm taking the downward direction to be positive)
The boat, moving at a presumably constant speed, then has 3.0 s to travel 19 m to the point of impact, which means its speed must be

Given:
The number of vibrations of the tuning fork is,

in,

To find:
The frequency of the fork
Explanation:
The frequency is the number of vibrations in 1 second
The frequency for the given fork is,

Hence, the frequency is 148 Hz.