learning|catalytics\" Log.out Session 41381252 Jurnpto 1() 3 4 5 6 7 8 9 10 11 1

Question

learning|catalytics" Log.out Session 41381252 Jurnpto 1() 3 4 5 6 7 8 9 10 11 12 13 14 15 16 You notice something is growing in a 100ml pot of liquid soap. You take 1ml of this liquid soap and perform a senal dilution and plate to determine the number of bacteria per 1ml in the liquid soap. On the 1:100,000 dilution you plate out 0.2ml and get a count of 37 colonies How many bacteria were present in the 100ml of soap in the pot (cfu/100ml)? 3.7 x 10 cfu/100ml 185 x 10 cu/100m D. 1 85 x 10 cha/100m

Explanation / Answer

The correct option is d) 1.85 x 109 colonies.

0.2 ml of final dilution is giving 37 colonies

Then 1 ml of final dilution will give 37 x 1 / 0.2 = 185 colonies.

So, 1ml of 1:100000 dilution is giving 185 colonies. Then 1ml of original solution will be 185 x 100000 colonies = 1.85 x 107 colonies = 1.85 x 107 colonies /ml.

Then 100 ml of original solultion will give 1.85 x 107 colonies x 100 = 1.85 x 109 colonies

=1.85 x 109 cfy/100 ml (option D).

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