Which is the best estimate for (6.3 times 10 Superscript negative 2 Baseline) (9.9 times 10 Superscript negative 3 Baseline) written in scientific notation?

Identify all the cases where non-probability sampling is used when attempting to study the characteristics of a large city. studies on every subject in the population divide a population in groups and obtain a sample studies with a limited amount of time demonstrate existing traits in a population studies with the nth person selected