Question

You have performed a serial dilution of an unknown sample and counted 73 CFU on a countable plate that was marked as a 10^-4 dilution and you used a 0-.1 mL to inoculate the plate. What is the population density of the original sample?

Answer 1

Hey there!:

To find the original sample population density, divide the conted colonies by the dilution factor and the inoculate:

= 73 / (10⁻⁴ * 0.1)

= 73*10⁵

Thus, the original sample's population density was 7.3*10⁶ or 73* 10⁵.

Hope this helps!