212 THE NORMAL AGE CT,ASSES. 



3^oungest age class, C'l. IS'ow, it may happen, that /// = ii ; in 

 that case the youngest age class does not exist hy itself ; but 

 is identical with C,. Again, it may occur, that m > n, in which 

 case Cv contains not only the youngest age class, but also 

 a portion, if not the whole, of the second age class. Hence, 

 the size of the several age classes may be expressed as follows, 

 assuming five age classes: — 



(1.) m<in. 



C. = "^ X ni 

 r 



Ci = - {n - m) 

 r 



Ca = - X n 

 r 



Cg = - X n 

 r 



C\ = - X // 

 r 



C'5 = ^XH 



r 

 Example : — 



,;( = 15 ; a = 20 ; r = 100 ; A = 1,000 acres. 



Then 



C'„ =10X15= 150 acres. 



Ci = 10 X 5 = 50 „ 



02=10x20= 200 „ 



Cg = 10 X 20 = 200 „ 



C4 = 10 X 20 = 200 „ 



C'5 = 10 X 20 = 200 „ 



Total = 1,000 acres. 

 (2.) VI = n. 



Example : — m = n = 20. 



C = — X m = 200 acres. 

 ?• 



Ci = - (n-m) =0 „ 

 r 



