As a Fraction: 1 / As a Decimal: feedback here So let s put some of these skills together to design dilution schemes - you don t want to be a lab grunt all your life, right.

Let s say I guesstimate that I have about 42 million CFUs per mL - I might want to start with a first dilution of about 1/1000, and plate that.

Population has changed since I wrote the above equation.

Remember the picture of the hell-to-count petri dish with 500 colonies.You would be counting all day and the CFUs overlap and it s a mess.Great, it didn t work the first time, so now we re going to do it again.I didn t think of that Well, we don t need to mix up all 100 liters.In other words, not trillions, not millions, but hundreds of billions.This rule nhl hockey pc game of thumb has the undeniable advantage of being easy to use.The prince looked at the mushy glutinous mass in his mother s cauldron with dismay.You definitely need at least 1 dilution, in case Frank is somewhere in the 300 or 400 per mL range.Richard Feynman, one of the most celebrated physicists in modern times, was famous for beginning his first-year honors physics class at Caltech by asking the students to estimate how many barbers work in Chicago.If Frank has 300 colonies in a 1/10th dilution, he has 3000 actual cells per mL, and that would be fatal.

You should practice this until it is second nature.

It is impossible to know the exact number of bacteria.Any more than 250 CFUs can cause overlap, and you ll underestimate the population size.Let s do the same thing again.He was giddy with emotion, but realized agenda msd 11.2 serial that convincing his mother would take some work.And clearly, this module is going to pick that method apart and pound it into the figurative whiteboard.Let s look at this in graphical form: Simple, right.Cue Sister 3, another explanation of soup, mothers, and true love, and you should be able to see it coming a third dilution.