Essential Genetics 6th Edition by Daniel Hartl

Exercise 3

Estimate the number of viable ? phage per milliliter (the phage titer) in a suspension from the following data. The original suspension was serially diluted through four dilutions of 100-fold each and one dilution of 10-fold. From the final dilution, a volume of 0.1 ml was mixed with a great excess of growing bacteria and then spread over nutrient agar in a petri dish and incubated overnight. The next day, 19 plaques were visible.