Actuarial Mathematics Flashcards
Accumulation
A = P * (1+i)^n
Interest for one time unit
I = i * P
Interest after n time periods
I = n * i * P
Accumulation n times
An = ( 1 + i )^n
Principal P accumulates
( 1 + i )^n * P
Accumulation factor
Let A(t1,t2) to be the accumulated value at time t2 of $1 at time t1
Accumulation factor general properties
- A(t,t) = 1
- Accumulation of a Principal P invested at time t1 is:
P * A(t1,t2)
- Principal of consistency
t1 <= t2 <= t3
- A(t1,t3) = A(t1,t2) * A(t2, t3)
A(t1, t2) is equivalent to
( 1 + i )^(t2-t2)
Compounded p-thly
Interest paid p times in each unit time period, i.e ever period 1/p
Nominal interest rate
i^(p) where the p is a subscript not a power
Nominal interest rate per time unit
interest is compounded p-thly with an interes rate of i(p)/p for any 1/p interval
A(t, t+1/p) = 1 + i(p)/p
Effective interest rate i
Total interest paid on $1 over one time unit
Effective Annual Rate (EAR)
The actual interest rate over a year, accounting for compounding
1 + i = ( 1 + i(p)/p) )^p
Annual Equivalent Rate (AER)
the interest rate that would yield the same accumulation after one year if compounded annually, rather than at different intervals
Annual Percentage Rate (APR)
This is EAR including extra fees
Time dependent nominal rate
i(p)(t), is the nominal interest rate applied over a specific term 1/p starting at a given time t
Accumulation factor for interest converted p-thly
A(t, t+1/p) = 1 +i(p)(t)/p
Force of interest
We define force of interest per unit time at time t as the limit:
d(t) = lim i(p)(t)
p -> infinity
Constant force of interest
A(t1,t2) = e^(d * (t2-t1)