A researcher did a 1 in 15 dilution of a bacterial culture and determined that the diluted culture has 6.6 x 10*4 CFU/mL. The researcher then took 1 mL of the undiluted original culture and mixed the aliquot with 14 mL of sterile culture broth. After mixing the resulting bacterial cell suspension, the researcher took 1 mL from this suspension and mixed the aliquot with 149 mL of sterile broth. Finally the researcher took 250 uL (microliter) of this final dilution and spread the aliquot on nutrient agar plate for CFU enumeration. What is the number of CFU/mL in the original undiluted culture and how many CFU does the researcher expect on the plate?
6.6 x 10*4 CFU/mL / (1/15) = 9.9 x 10*5 cells/mL
The number of CFU/mL = 110 but I thought it was this answer below but its wrong.
9.9 x 10*5 cells/mL / (15 x 150) (10) = ?
9.9 x 10*5 cells/mL / (2250) (10) = 44 cells