You have just been hired by the EPA! Your first assignment is to determine whether a well that supplies water to a town is safe for drinking before you can try to identify the identity of the potential culprit. In order to consider the well safe it must contain less than 6.6 x 10^5 CFU/mL. First, you subsample the well by taking a 500 mL sample of water and bring it back to your lab. From the 500 mL sample, you take 17,250 L and add it to 0.185 L of water. Then you take 6.5 mL and add it to 51,130 L. Finally, you take 850 L and add it to 9.15 liters. You then plate 150 L and observe 292 colonies after incubation. Answer the following questions.
Question 44
2 pts
What was the FINAL concentration?
O8.93x10^-7
O1,947 cells/mL
O1,947 CFUs
O292 cells/15mL
O1.9x10^5 cells/mL
O2.18x10^9 cells/mL
O2.18x10^9 CFUs
Question 45
2 pts
What was the TOTAL dilution factor?
8.93x10^-7
O1.09x10^12 cells
O1.9x10^5 cells/mL
O292 cells/15mL
O2.18x10^9 CFUs
O1,947 cells/mL
Question 46
2 pts
What is the ORIGINAL starting concentration of the well?
O292 cells/15mL
O2.18x10^9 cells/mL
O1.09x10^12 cells
O8.93x10^-7
O1,947 cells/mL
O2.18x10^9 CFUs
