Question

A 1 ml sample of culture liquid contained 1000 viable bacterial cells. You serially diluted it twice, performing 10-fold or 1/10 dilutions into a final volume of 1 ml each time. As a result you have three tubes with 100, 10-1, or 10-2 of diluted culture. How many total cells are in the 1 ml of your 10-2 dilution tube?

Answer 1

Answer:

there are 10 viable bacterial cells in 1 ml in the 1/100 dilution tube

Explanation:

in 1ml there is 1000 viable bacterial cells → diluted with 9 ml of solvent (10 ml in total)→  1000 viable bacterial cells in 10 ml (fist tube)

now we take 1 ml of the first tube into the second empty tube → has 1000/10 = 100 viable bacterial cells on 1 ml → diluted with 9 ml of solvent (10 ml in total)→  100 viable bacterial cells in 10 ml (second tube)

then we take 1 ml of the second tube into the third empty tube → has 100/10 = 10 viable bacterial cells in 1 ml → diluted with 9 ml of solvent (10 ml in total)→  10 viable bacterial cells in 10 ml (third  tube)

therefore there are 10 viable bacterial cells in 1 ml in the 1/100 dilution tube