Determine the z score given the mean of 172, standard deviation of 8 and x - value or 192

$\displaystyle Z$ score = $\displaystyle {x} - {\mu} / {\sigma} $

So it goes like this...

Z = 192-172/8

Z = 2.5

Now i look back in the book and find the z score on the table.

i get a value of 0.9938...

what am i doing wrong?