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If you have a bacterial culture with 2.3 x 104 cells/ml, how much of a 1:7...

If you have a bacterial culture with 2.3 x 104 cells/ml, how much of a 1:7 dilution would you have to plate in order to get 250 colonies growing on the plate?

Please answer in micro liters.

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Answer #1

CFU/mL= number of colonies/(volume plated in mL dilution)

dilution =1/7

number of colonies=250

CFU/mL=2.3 x 10^4 CFU/ml

2.3 x 10^4 CFU/ml= 250/(volume plated in mL 1/7)

volume plated in mL/7=250/2.3 x 10^4

volume plated in mL=(250/2.3 x 10^4)7

volume plated in mL=0.0761

1 mL= 10^3 microliters

so 0.0761=76.1 microliter

volume of of 1:7 dilution would you have to plate in order to get 250 colonies growing on the plate =76.1 microliter.

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