VALUES OF NORMAL PROBABILITY INTEGRAL. 119 



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

 OR THE NORMAL PROBABILITY INTEGRAL CORRESPOND- 



ING TO VALUES OF ; OR THE FRACTION OF THE AREA 



a 



OF THE CURVE BETWEEN THE LIMITS AND + , OR 







AND - . 



a 



Total area of curve assumed to be 100,000. 

 x = deviation from mean. 

 a = standard deviation. 



