2023 THREE(b)

The graph below shows the function $y=f(x)$.

For the function above:
(i) Find the value(s) of $x$ where $f(x)$ is continuous but not differentiable.

(ii) Find the value(s) of $x$ where $f^{\prime }(x)=0$ and $f^{\prime \prime }(x)<0$ are both true.

(iii) What is the value of ${\lim }_{x\to 6}f(x)$?

State clearly if the value does not exist.