Question 157889
The normal distribution curve has the formula,
{{{P(z)=(1/sqrt(2*pi))e^((-1/2)*z^2))}}}
{{{ graph( 300, 300, -5, 5, -.5, .5, (0.3989)(2.718)^((-1/2)*x^2))}}}
The area under the entire curve from {{{z=-infinity}}} to {{{z=infinity}}}
equals 1. 
Since the curve is symmetric, the area at from {{{z=-infinity}}} to {{{z=0}}} would be 1/2. 
For the value of Z=-1.03, the area equals 0.1515.
There are tables that have values of area under the curve based on the z value.

Instead of tables, you can also use the EXCEL function NORMSDIST to calculate the value also (NORMSDIST(-1.03)=0.1515).