Answer:
1.37 x CFU/mL
Explanation:
First, the dilution factor needs to be calculated.
Since four 9 ml dilution blanks were prepared, the dilution factor that yielded 137 colonies is of .
Next is to divide the colony forming unit from the dilution by the dilution factor:
137/ = 137 x
In order to get the CFU/ml, divide the CFU from the dilution by the plated volume (1 mL) from the final dilution tube.
137 x /1 = 1.37 x
Hence, the CFU/ml present in the original <em>E. coli </em> sample is 1.37 x .
cfu/ml = (no. of colonies x dilution factor) / volume of culture plate