If you need to do a 1:20 dilution on a culture to get acceptable plate counts, how many milliliters of original sample will you add to a final volume of 0.1 mL? For this course, a 1:20 dilution is 1 part culture to a final volume of 20 parts. For example, 1 mL culture and 19 mL sterile DI water. Report your answer to 4 decimal places

Question

Chemistry

Kathy Bradshaw

6 May, 11:34

If you need to do a 1:20 dilution on a culture to get acceptable plate counts, how many milliliters of original sample will you add to a final volume of 0.1 mL? For this course, a 1:20 dilution is 1 part culture to a final volume of 20 parts. For example, 1 mL culture and 19 mL sterile DI water. Report your answer to 4 decimal places

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Answers (1)

Know the Answer?

Allisson Valentine · Answer 1

0.0050 mL

Explanation:

First we divide the final volume by 20:

0.1 mL / 20 = 0.005 mL

So if we add 0.005 mL of the original sample to 0.095 mL of sterile DI water, we're left with 0.1 mL of a 1:20 dilution.

Rounding up 0.005 mL to four decimal places, the answer thus is 0.0050 mL.