Rule. Divide the amount by the annuity, and multiply the quotient
by 8 times the interest of £l for one year; add to this the square of the
difference between 2, and the interest of £l for a year, and extract the
square root of the sum ; from this result subtract the difference between
2 and the interest of £ 1 for a year, and divide by twice the interest of
£l for one year.
Example. How many years must an annuity of £325 be forborne
to amount at 3^ per cent simple interest to £4650 15 0?
a ~ 325
s = 4650.15
325)4650.15 ( 14.31 =
1400
1300
1001
915
.325
325
11448
2862
4.0068 =
2.
.035
1.965 = 2 — i
1.965
9825
11190
11685
1965
.01 = 2i
(2 - if = 3.861225
8 i —= 4.0068
a
8 _ + (2 - iy 1.868025(2.805 = V 8z— + (2
4. 1.965 = 2 - i
48)386 .07).840=\/8t ~ +(2—¿Y—(2 — 0
12 years
divid
Ru
years
by the
one.
Exc
£325
325)46
18. I
done by
sum of
If we
pression
For
covei
a Ion
ever,
low’s