Здравствуйте, Руслан Чернов!
Посмотрите такой вариант
program koef;

uses crt;

type
TFun = function(x:Double):Double;

var
mx,my,mz: Double;
sx,sy,sz: Double;
ax,ay,az: Double;
bx,by,bz: Double;
k:Double;

function PLaplas(x:Double):Double;far;
begin
PLaplas:=Exp(-x*x/2)/Sqrt(2*Pi);
end;

function ISimpson(a,b:Double;n:Integer;f:TFun):Double;
var
i:Integer;
h:Double;
y:Double;
begin
h:=(b-a)/n/2;
y:=f(a)+f(b)+f(b-h);
for i:=1 to n-1 do
begin
y:=y+4*f(a+h*(2*i-1))+2*f(a+2*i*h);
end;
y:=y*h/3;
ISimpson:=y;
end;

function FLaplas(x:Double):Double;
var
y:Double;
begin
y:=ISimpson(0,Abs(x),10000,PLaplas);
if x<0 then y:=-y;
FLaplas:=y;
end;

function P(a,b,m,s:Double):Double;
var
x1,x2:Double;
begin
x1:=(a-m)/s;
x2:=(b-m)/s;
P:=FLaplas(x2)-FLaplas(x1);
end;

begin
clrscr;
Write('mx=');Readln(mx);
Write('my=');Readln(my);
Write('mz=');Readln(mz);
Write('sx=');Readln(sx);
Write('sy=');Readln(sy);
Write('sz=');Readln(sz);
Write('ax=');Readln(ax);
Write('bx=');Readln(bx);
Write('ay=');Readln(ay);
Write('by=');Readln(by);
Write('az=');Readln(az);
Write('bz=');Readln(bz);
k:=P(ax,bx,mx,sx)*P(ay,by,my,sy)*P(az,bz,mz,sz);
Writeln('k=',k);
Readln;
end.