What is the Correct Approach for Calculating Connected Rates of Change?

[AntSC]

Homework Statement

Homework Equations

The Attempt at a Solution

My problem is with part ii)
To me, my logic seems sound for the rate of change of depth but apparently it's wrong.
Does anyone see what I'm missing?
Thanks

 

[SteamKing]

Homework Statement

View attachment 93778

Homework Equations

The Attempt at a Solution

View attachment 93779My problem is with part ii)
To me, my logic seems sound for the rate of change of depth but apparently it's wrong.
Does anyone see what I'm missing?
Thanks

In part ii) check your arithmetic. What is 4 ⋅ 14?

 

[AntSC]

Oops! Thanks. Working too fast.