Dilution Dilution Factor Colony Count

1:10000 10000 4720
1:50000 50000 1020
1:250000 250000 194
1:1000000 1000000 23

can you tell me how to calculate the colony count of the hypothetical water sample is _______CFU per ml.Thanks!

To calculate the colony count (CFU per ml) of the hypothetical water sample, you can use the dilution factor and the number of colonies observed in the diluted samples.

1. Start by identifying the dilution factor of each sample. The dilution factor represents how many times the original sample was diluted to obtain the final sample.

2. Calculate the concentration of the diluted samples by dividing the colony count by the dilution factor.

3. Take the concentration of the last dilution (highest dilution factor) and multiply it by the inverse of the dilution factor to get the concentration of the original sample.

For example, let's calculate the colony count for the hypothetical water sample given the dilution factors and colony counts provided:

1. For the dilution 1:10000, the dilution factor is 10,000, and the colony count is 4,720. The concentration of this dilution is calculated as 4720/10000 = 0.472 CFUs/ml.

2. For the dilution 1:50000, the dilution factor is 50,000, and the colony count is 1,020. The concentration of this dilution is calculated as 1020/50000 = 0.0204 CFUs/ml.

3. For the dilution 1:250,000, the dilution factor is 250,000, and the colony count is 194. The concentration of this dilution is calculated as 194/250000 = 0.000776 CFUs/ml.

4. For the dilution 1:1,000,000, the dilution factor is 1,000,000, and the colony count is 23. The concentration of this dilution is calculated as 23/1000000 = 0.000023 CFUs/ml.

5. To find the colony count for the original sample, we'll take the concentration of the last dilution (0.000023 CFUs/ml) and multiply it by the inverse of the dilution factor (1/1,000,000). This gives us 0.000023 ×(1/1,000,000), which equals 0.000000023 CFUs/ml.

Therefore, the colony count for the hypothetical water sample is 0.000000023 CFUs/ml.