Your score in a recent test was $0\mathrm{.}5$ standard deviations above the average, how many people $($in percentage$)$ scored lower than you?

Example: Your score in a recent test was $0,5$ standard deviations above the average, how many people scored lower than you did?

Between $0$ and $0,5$ is $19,1\%$

Less than $0$ is $50\%($left half of the curve$)$

So the total less than you is:

$50\%+19,1\%=69,1\%$

In theory $69,1\%$ scored less than you did $($but with real data the percentage may be different$)$

How to find $19,1\%?$ I didnt understand the solutions