essie is working with a 100% stock concentration of Clorox. She decides to add 150 µL of bacteria to a tube containing 2 mL of nutrient broth and then adds 200µL of the Clorox stock to the tube as well. What is the unknown concentration of the tube?

8.5%

Explanation:

The unknown final concentration can be found out by the dilution formula C1V1 = C2V2

where,

C1 = Starting concentration = 100%

V1 = Starting volume = 200μL

C2 = Final concentration

V2 = Final volume = 2350μL (2000 + 150 + 200)

So,

100 * 200 = C2 * 2350

C2 = (100 * 200) / 2350

= 20000 / 2350

= 8.5%