Briefly explain two different ways to decide when to stop testing.
Answer: One way is to use the ratio of seeded errors and real errors to discovered seeded errors to discovered real errors to project or estimate the number of real errors that may still be left. Use that estimate to decide if testing may be stopped.
Another way is to observe the problem discovery rate and the accumulative number of problems discovered. As the accumulative problem discovered start to level off, then one may start to consider stop testing.