Question

A culture is diluted in the following manner 1 mL of starting cultures diluted into 9 mL of water, then 1 mL of that new dilution is diluted into a second tube of 9 ml water. What is the dilution factor of the second tube? Explain.

Answer 1

The second tube has a dilution factor of 1:100, calculated by multiplying the individual dilution factors of two consecutive steps (1:10 each).

Step-by-step explanation:

To determine the dilution factor of the second tube, we will consider the successive dilutions. Initially, the culture is diluted by adding 1 mL to 9 mL of water, resulting in a 1:10 dilution factor. In the next step, 1 mL of this dilution is added to another 9 mL of water. Therefore, the second dilution also has a dilution factor of 1:10 relative to the first dilution tube.

Since we are performing serial dilutions, to find the overall dilution factor of the second tube relative to the original culture, we need to multiply the individual dilution factors of each step: 10 (from the first dilution) × 10 (from the second dilution) = 100. So the second tube has a dilution factor of 1:100 relative to the original culture.