lie between the two values -B and +B as given by the area under the 

 curve from -B to +B can be computed and set equal to A as in equation 

 (12). 



P (-B<Z<B)= A (12) 



If, for example, B equals 1.65, then A is 0.90. That is, nine times 

 out of ten, z will lie between -1.65 and +1.65. 



Some operations on equations (11) and (12) can now be carried out. 

 The first result is equation (13), and the purpose of the operations is 

 to get the symbol .^E inside the inequalities and ^ outside the 

 inequalities. 



C- (7^/2)71 



-B < — ~ <B. 



Equation (13) can be written as 



(13) 



B< v/(l-Z)E/N 2y(|-f)/N '^'^- (14) 



This yields 



< ^ < R+ "^ 



and 



B+ ^^ < '^ <B+ , 



zVTFJTTn y(|-|^)E/N 2 ^/(|-f )/N 



_By(i-|:)/N + yV2 , bV(|_ZI)/n + -/^/2 

 3_^ < _L < 4_1 



(15) 



I a/e ^ (16) 



Finally, by inverting equation (16) the result is 



<-A< __-_4==r— • (17) 



yV'2+By(|-Z)/N -/^/2-B vTFJO/N 



The mean amplitude gives an estimate of E which will be called E 



m 



15 



