XXVIII] 



Introduction 



xlix 



ORY/' 



Write & = c, 6, = 10c , 6 2 = lOOc,, 6 3 = 1000c 3 . 



Then our equations are 



23650 = b, x -31000 + 6 2 x -24800, 



1-83345 = 6, x -24800 + b, x -35662, 



45603 = 6 x -24800 + 6 2 x -35662, 



2 48808 = 6, x -35662 + b 3 x -60966 ; 



giving 6 = - -58626, .-. c = - -58626, 



b. = 1-686453, c, = '016,8645, 



6, = 9-59613, c, = -959,613, 



6 3 = - 1-532,144, c, = - -001,532,144, 



and the required cubic is 



y = - -58626 + -959,6133; + '016,8645^ - -001,532,144^. 



45, , , , i i , , i 



K) 



25 * 



15 



20 



25 3O 35 40 45 



Age of Bride. 



The graph of the cubic and the observations are given in the accompanying 

 diagram. If X and Y be the actual ages of bride and groom, then 



Y = 61-30457 - 4-344.941Z + -157.0553Z' - -001,53214Z 3 . 



For higher parabolic curves fitted to the same data, see Biometnka, Vol. n. 

 pp. 2122. 



B. g 



