An agricultural scientist wanted to estimate the total number of viable fungal spores (Fusarium oxysporum) in a 60 cm³ soil suspension. They carried out the following two serial dilutions:

• 0.5 cm³ of the original suspension was mixed with 14.5 cm³ of sterile distilled water to make Solution B.
• 2 cm³ of Solution B was mixed with 8 cm³ of sterile distilled water to make Solution C.

The scientist transferred 0.15 cm³ of Solution C onto a growth medium plate. After incubation, 42 distinct fungal colonies grew on the plate.