COMPOUND INTEREST. 
a year, 
; present 
ontinue. 
annum, 
archased 
mum for 
n equiva- 
hould be 
2 nearly. 
By transposition 
by logarithms, 
— n log (1 + i) — log (I — 
or n log (1 + 0 — — log (l — 
dividing each side by log (1 + i), 
- ~'° s(1 ~ f) 
log (1 + i) 
For how many years may an annuity of £30 be purchased for 
«£551 15 3, when interest of money is 3^ per cent? 
p = 551.7625 
.035 
27588125 
16552875 
30)19.3116875 
.64372291 = — 
I. « 
.35627709 = 1 — 
— log ^1 — 
log (1 + ij 
i = .035 
0.4482121 
.0149403 “ 30 years. 
54. To find (i) the rate of interest— 
(Art. 50.) 1 " (1 + l) 
multiplying each side by i, and dividing by a, 
7,1 = i - a + o~ B i 
to 
by transposition,