Approximately 1% of red blood cells are destroyed per day. I was wondering if we could derive this from the assumption that all red blood cells have a lifespan of 120 days.
I think we should assume that the concentration of red blood cells is constant and that red blood cells are continuously created and destroyed at a constant and equal rate.
The formula for the Mean Time to Faliure says that $t=\frac1p$, where $t$ is the lifetime of an object and $p$ is the fraction of objects that fail.