Question

Plating 1.0 ml. of a sample diluted by a factor of 10 produced 43 colonies. What was the original concentration in the sample?

Answer 1

`4.3` CFU/mL

Step-by-step explanation:

Given -

Dilution factor for sample
`= 10`

Number of colonies produces
`= 43`

Volume of sample before dilution
`= 1`mL

Volume of sample with dilution

`= 1* 10\\= 10`mL

As we know,

Original concentration of sample is equal to CFU divided by the sample volume.

Thus, original concentration in the sample

`= (43)/(10) \\= 4.3` CFL/mL