VALUES OF NORMAL PROBABILITY INTEGRAL. 119 



TABLE IV.-TABLE OF THE HALF CLASS INDEX (*a) VALUES 

 OF THE NORMAL PROBABILITY INTEGRAL CORRESPOND- 

 ING TO VALUES OF -; OR THE FRACTION OF THE AREA 



a 



OF THE CURVE BETWEEN THE LIMITS AND +-, OR 



a 



AND - . 



a 



Total area of curve assumed to be 100,000. 

 x = deviation from mean. 

 a standard deviation. 



