XXVIII] Introduction 



Write b = c , b, = 10c„, 6 2 =100c 2 , 6 3 =1000c 3 . 



Then our equations are 



•23650 = b„ x -31000 + b, x -24800, 



1-83345 = b, x -24800 + 6 3 x -35662, 



•45603 = b u x -24800 + b. 2 x -35662, 



248808= 6, x -35662 + 6 3 x -60966; 



giving b„ = - -58626, .-. c„ = - "58626, 



6, = 1-686453, c 2 = -016,8645, 



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



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



and the required cubic is 



y= - -58626 + -959,613a; + -016,8645a? - 001,532,144^. 



xlix 



30 



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 2 - -001,53214X 3 . 



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

 pp. 21—22. 



B. g 



