I give you a very expensive strain of E. coli containing 10^12 CFU/ml and tell you that I need exactly 10ml of the same E. coli culture at a concentration of 10^4 CFU/ml (I don't want any excess culture). Using a dilution series, how would you get the correct concentration and volume of bacteria? Make this a realistic scenario.
If we start with 10^14 CFU/ml, then we need to dilute it appropriately to end up with 10^4 CFU/ml.
If we take 1 ml of the original culture and dilute it into 1000 mL, then we ...