USEFUL FORMULA FOR TWO LIVES. 
When m,—1 is greater than m, the single premium is 
sh (Nu, i= Nm) = Nimo = No zo) 
2 : D., : 
the annual premium is 
1(D, my FT (Nm, mit Nt et) oN, uger N ot, = : 
a 
The single premium for the term of t years is, 
When m —1 is greater than m, 
2 r(Nns mt~Nontetmptims Nosy Notts my 0)~ No + No mt). 
2 nv, 
+ N,mat + Not, my+t—1 | ; 
Dn, mi 
When m,—1 is greater than m, 
Ln ra” Ninvi=1, ptt Nr, m+ None, he 
2 BD. 
(Nes + Nott, m+) + Noir, pT Noy, m 
TED 5 : 
Substituting in the denominator of these last two formulae 
Not met None, mihi=1 for D,;, mys WE have the annual premium. 
The probability of a life aged m dying before a life aged my, is 
Derk Nurs m= ines 
hi