The price of insurance depends ultimately on the risk the insurer is taking on on behalf of the customer. Simply put, this will depend on the chance of the insured event occurring, and the likely cost of the outcome. The way insurers calculate this risk, and quantify the amount of the premium, is through the use of what is known as actuarial science. Using certain probability and statistical mathematical models, the insurance company can predict with a fair degree of accuracy, the approximate cost of future claims.
For example, supposing a someone wishes to insure their $100,000 home against fire. For arguments sake, lets assume that 1 in a 1000 homes in this area burn down every year. This would mean that just to break even, on the mathematical model, the insurance company would have to charge $100 a year for the premium. What the insurance company will in fact do is charge something more than $100, say $120. This extra $20 will cover the overhead costs of the insurance companys operation. It will also cover an amount for profit of the insurance company. The only other way the insurance company generates profits is by investing all the policy premiums it is paid. That...