00:02
A plague assays performed beginning with 1 militer of solution containing bacterial phages.
00:07
The solution is serially diluted four times by combining 0 .1 militer of the sequential dilution with 9 .9 militer of liquid media.
00:17
So they find out that 1 .1 militer of final dilution is plated in the plaque acid and it produced 29 plagues.
00:27
So the question asks you to calculate the initial density of the bacteria phages before dilution.
00:35
So the final density actually can be calculated by the number of plate divided by the volume.
00:42
So we can plug in the number.
00:43
We know that after the dilution, the number of the plague that the grow on the plate is 29.
00:49
Now, the volume here is 0 .1 because the 0 .1 militer of the final dilution is plated.
00:55
So 29 divided by 0 .1 mil equals 290 cfu per mill year.
01:03
So this is the final density after all the dilutions.
01:09
Okay.
01:10
Now, the question also gives us the information says to calculate the initial phage density, you can use the final density times the dilution factor...