1. What is the statistically significant number range of colonies that may be counted on a Petri dish (for the pour plate method)?
2. Scientific Notation. Fill in the missing information.
a) 4.5 x 109 = _______
b) 50 x 107 = _______
c) 2300 x 1010 = _______
d) 0.54 x 108 = _______
3. You wish to determine viable counts on a culture of Bacillus subtilis. You begin by pipetting 1 ml of culture into 99 ml of sterile water. After mixing the dilution well you make a series of 4 further dilutions of 10-1 each. From the three most dilute samples, you prepare three pour plates using 1 ml in each. After incubation you find the plate counts of the plates are 16, 245 and 890 respectively.
a) Show the dilution scheme.
b) What is the estimated viable count (cells/ml) in the original culture?
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