| $z$ | $\mathrm { P } ( 0 \leq Z \leq z )$ |
| 0.6 | 0.226 |
| 0.8 | 0.288 |
| 1.0 | 0.341 |
| 1.2 | 0.385 |
| 1.4 | 0.419 |
The random variable $X$ follows a normal distribution with mean $m$ and standard deviation 5, and the probability density function $f ( x )$ of the random variable $X$ satisfies the following conditions.\\
(가) $f ( 10 ) > f ( 20 )$\\
(나) $f ( 4 ) < f ( 22 )$\\
When $m$ is a natural number,\\
$\mathrm { P } ( 17 \leq X \leq 18 ) = a$. Find the value of $1000a$ using the standard normal distribution table below. [4 points]
\begin{center}
\begin{tabular}{ | c | c | }
\hline
$z$ & $\mathrm { P } ( 0 \leq Z \leq z )$ \\
\hline
0.6 & 0.226 \\
\hline
0.8 & 0.288 \\
\hline
1.0 & 0.341 \\
\hline
1.2 & 0.385 \\
\hline
1.4 & 0.419 \\
\hline
\end{tabular}
\end{center}