Question

On two sets of subsequent duplicate plates, you have generated the following counts:

a. 10⁻²=129 and 142
b. 10⁻³=15 and 20
What is your ONE final reported count with correct units for this sample of pasteurized milk?

Answer 1

The final reported count for this sample of pasteurized milk is 1.69 x 10³ bacterial cells. Given the counts from the two sets of subsequent duplicate plates and the dilution process, the average count of colonies on each plate was calculated. The final count is obtained by multiplying the average count by the dilution factor.

Step-by-step explanation:

The final reported count for this sample of pasteurized milk is 1.69 x 10³ bacterial cells.

Given the counts from the two sets of subsequent duplicate plates (a. 129 and 142, b. 15 and 20) and the dilution process described, the average count of colonies on each plate was calculated. The final count is obtained by multiplying the average count by the dilution factor from the dilution process.

In this case, the dilution factor for these plates is 10³, as each subsequent dilution resulted in a 10x decrease in concentration. Therefore, the final count is 10³ multiplied by the average count of colonies, which is 1.69. The correct units for this count are bacterial cells.