Thirty-six colonies grew in nutrient agar from 1.0 ml of undiluted sample in a standard plate count. How many cells were in the original sample?

36 cells are expected to be in the original sample.

Explanation:

The number of colonies found in the agar nutrient medium is a viable cell count.

The colonies formed shows the number of actively multiplying bacteria. Viable cells are known from the plate count method in which the bacterial colony is seen and counted. The colonies exhibit roughly the number of cells of bacteria present in the original sample and form colonies after plating.

The advantage of counting cells by the plate count is that only viable cells can be counted.

So, 36 cells in the original sample yield 36 viable colonies on the agar medium.