Well 7/3 = 2 (more or less - the whole calculation is very approximate obviously). The basic idea is if you have 100 people (of a broad spectrum of ages) you'd

Well 7/3 = 2 (more or less - the whole calculation is very approximate obviously). The basic idea is if you have 100 people (of a broad spectrum of ages) you'd expect about 1 of them to die each year.