Answers for Serial Dilution Problem # 5
- Which is the countable plate? "D" #CFU 40
- What is the SDF? 1/200
- Calculate the ITDF:
- 0.1 ml / 0.1 ml + 0.9 ml = 0.1 ml / 1.0 ml = 1/10
- See Above = 1/10
- 0.01 ml / 0.01 ml + 0.99 ml = 0.01 ml / 1.0 ml = 1/100
- See Above = 1/100
- Calculate the TSDF for the countable plate.
- 1/10 x 1/10 x 1/100 x 1/100 = 1,000,000
- Calculate the PDF for the countable plate.
- Calculate the FDF for the countable plate.
- FDF = SDF x TSDF x PDF
- FDF = 1/200 x 1/1,000,000 x 1/10 = 1/2,000,000,000
- Calculate the CFU/ml for the countable plate.
- CFU/ml = #CFU x 1/FDF
- CFU/ml = 40 x 1 / 1/2,000,000,000
- = 40 x 2,000,000,000
- = 80,000,000,000 CFU/ml
- = 8.0 x 10
CFU/ml
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