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1) 28/0.1x500x10= 14000000 = 1.4 x 10^6 2) 28/0.1= 280 = 2.8 x 10^2. [(0.1)/(0.1

ID: 162860 • Letter: 1

Question

1) 28/0.1x500x10= 14000000 = 1.4 x 10^6

2) 28/0.1= 280 = 2.8 x 10^2. [(0.1)/(0.1+9.9)]^5 = 10^-10 = 10^10. (2.8x10^2)x(10^10)=2.8x10^12

I dont know what answer is correct or if I have mistakes, please help :(

Problem 6.26 A plaque assay is performed beginning with 1 mL of a solution containing bacteriophages. This solution is serially diluted 5 times by combining 0.1 mL of each sequential dilution with 9.9 mL of liquid medium. Then 0.1 mL of the final dilution is plated in the plaque assay and yields 28 plaques. previous l 6 of 6 l return to assignment Part A What is the initial density of bacteriophages in the original 1 mL? Recall that initial phage density (plaque number/mL) x dilution factor Enter your answer to two significant digits (for example: 1.1 102). plaque-forming units/mL Submit My Answers Give Up Continue Provide Feedback

Explanation / Answer

Answer:

Dilution factor after 5 serial dilutions= 1/10^10

How?

0.1+9.9mL= 1/100 fold dilution

5 serial dilutions =1/10^10 fold dilution

CFU/ml = ?

Dilution factor= 1/100^5

Number of colonies= 28

Volume of sample = 0.1 mL to the plate

cfu/ml = (no. of colonies)/ dilution factor x volume of culture plate

cfu/ml = (28)/ (1/10^10 x 0.1)


cfu/ml = 28 x 10^11