166 ESSAY ON PROBABILITIES. 



middle classes, that from the age of 15 to that of 65, 

 the average may be represented as follows : of 100 

 persons aged 15, one dies every year till the age of 65. 

 But the mean duration of life will serve to give a more 

 precise idea, and a simple rule may be given, which 

 will, for rough purposes, represent the Carlisle table 

 between the ages of 10 and 60. Of persons aged 10 

 years, the average remaining life is 49 years, with a 

 diminution of 7 years for every 10 years elapsed ; thus 

 of persons aged 20 years, the average remaining life is 

 49-7 or 42 years ; at 30 years of age, 35 years. The 

 following list of tables will be followed by some notice 

 of each. 



