\section*{Part B}
The travel time for Louise, in minutes, between her home and work, can be modeled by a random variable $X$ that follows a normal distribution with mean 28 and standard deviation 5.
\begin{enumerate}
  \item Calculate $P ( X \leqslant 25 )$.
  \item Calculate the probability that the travel time is between 18 and 38 minutes.
  \item Determine the travel duration $d$, rounded to the nearest minute, such that $P ( X \geqslant d ) = 0.1$.
  \item Louise has now found a faster route. From now on, the travel time, in minutes, can be modeled by a random variable $Y$ that follows a normal distribution with mean 26 and standard deviation $\sigma$.\\
We know that $P ( Y \geqslant 30 ) = 0.1$.\\
Determine $\sigma$ rounded to the nearest hundredth.
\end{enumerate}