i need # 3 Dilution factors can be represented many different ways, as a fractio

Question

i need # 3

Dilution factors can be represented many different ways, as a fraction, a decimal, a ratio, or an exponent. For plates A and B write out these dilution factors in three different ways. Dr. Ellis was taught to represent dilution factors as negative exponents (For example 10^-3). Therefore if Dr. Ellis counts 34 colonies on the plate a with 10^-3 dilution factor, how many bacteria are in the original sample? Write the number in both scientific notation AND written out with all relevant zeros added. Why might it be more appropriate to write the dilution factor as a negative, rather than a positive exponent? This experiment aims to determine the CFU/gram of meat. Given that fact, how does the dilution factor change if we plate 1 ml of the diluted sample? What about 0.1 ml of the same sample? Label the dilution factors for each Petri dish on the diagram. Use whatever representation makes best sense to YOU.

Explanation / Answer

Ans.) First of all calculate the (CFU) per gram of meat sample by dividing the number of colonies by the dilution factor. The number of colonies per ml observed should display the accuracy of the method.

CFU/ml is calculated by the prescribed formula and given below-

If 0.1 ml of meat sample is added to 9.9 ml of water, then

Volume = meat sample volume + water volume

              = (0.1+ 9.9) = 1.0

Dilution factor = 10.0ml / 0.1ml = 100

Hence, the meat sample is diluted by a factor of 100.

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