Question 314993
Find the z-score.
{{{z=(x-mu/sigma)}}}
{{{z=(19-16)/3=1}}}
{{{P(1)=0.8413}}}
That probability value is that the process will take 19 hours or less.
To calculate for greater than 19 hours, recall that
P( <= 19)+P( > 19)={{{1}}}
P( > 19)={{{1-0.8413=0.1587}}}