In life tables, what does the notation _n p_x represent?

• A. Probability that a life aged x survives to age x+n
• B. Probability of death within n years
• C. The force of mortality over n years
• D. The net single premium for a life aged x+n

Answer: (A)

The notation _n p_x represents the probability that a life aged x survives for n years, i.e., remains alive at age x+n given they are alive at age x. For example, a person aged 40 has probability _20 p_40 of reaching age 60. This is a survival probability over a finite horizon.

If you want the chance of dying within n years, that’s 1 minus this survival probability (often written as _n q_x). The other options describe different concepts: the force of mortality over an interval is a rate, not a probability, and the net single premium is a monetary amount used in pricing, not a probability.