You diluted a starting culture of E. coli 1:10 ten times. From these dilutions you plated 0.1mL of each dilution onto an agar plate. You then counted the number of bacterial colonies that grew after incubation (see below). Give the average estimated starting concentration of bacteria per milliliter from the plates shown below. Don't forget units! Show your work.
1 x 10^-9 dilution
(1/1,000,000,000)
1 x 10^-10 dilution
(1/10,000,000,000)