試題詳解

36. What is the cell density of a bacterial culture if plating 0.2 ml of a 10⁵-fold dilution of the culture yields 45 colonies.
(A) 4.5 × 10⁶
(B) 9.0 × 10⁶
(C) 2.25 × 10⁷
(D) 4.5 × 10⁷
(E) 9.0 × 10⁷