Key Formulas & Equations
A = final amount, P = principal, r = annual rate, n = compounding periods per year, t = years
Annuity PV: PV = PMT ร [1 โ (1 + r)โt] / r
Force of Mortality: ฮผx = โd/dx [ln S(x)]
Net Premium: P = E[Benefits] / E[Annuity Factor]
Credibility Premium: Pcred = Z ร Pobserved + (1 โ Z) ร Pprior
Core Concepts
Mathematical functions describing the probability of survival to a given age. The survival function S(x) gives the probability a newborn survives to age x. Foundation of life insurance mathematics.
Events whose occurrence depends on human life โ death, survival, disability. Actuaries calculate probabilities of these events to price insurance and annuity products.
The study of aggregate claims and the financial stability of insurers. Includes modeling claim frequency, claim severity, and calculating ruin probabilities.
Combining prior information (industry data) with current experience (company data) to produce more accurate premium estimates. Higher credibility weight goes to more reliable data.
Brownian motion, Poisson processes, and Markov chains model the random evolution of financial and insurance systems over time.
Worked Examples
A policyholder invests $10,000 at 5% annual interest compounded monthly for 10 years.
A = 10,000 ร (1 + 0.05/12)120 = 10,000 ร 1.647 = $16,470
For a 1-year term life insurance of $100,000 on a 35-year-old with q35 = 0.002 and i = 5%:
NSP = 100,000 ร 0.002 / 1.05 = $190.48
A 65-year-old receives $2,000/month for life. Using a65 = 12.0 and i = 5%:
PV = 2,000 ร 12 ร 12.0 = $288,000
Practice Problems
Answer: A = 5,000(1 + 0.015)20 = $6,734
Answer: NSP = 50,000 ร 0.001 ร v1 = 50 ร 0.9615 = $48.08 (term portion)
Answer: 10p40 = eโ0.02ร10 = eโ0.2 = 0.8187
Answer: Z = (600,000 โ 500,000)/50,000 = 2.0, P(Z > 2.0) โ 2.28%
Answer: P = 200,000 ร 0.05 / 8.0 = $1,250