Solve the Problem $\mathrm { a } _ { \mathrm { n } } = 20 ( 3 ) ^ { \mathrm { n } - 1 }$

Multiple Choice

Solve the problem.
-The population size of a culture of bacteria triples every day such that its size is modeled by the sequence $\mathrm { a } _ { \mathrm { n } } = 20 ( 3 ) ^ { \mathrm { n } - 1 }$ , where $\mathrm { n }$ is the number of the day just beginning. Find the size of the culture at the beginning of the third day and the size of the culture originally.

A) 540 bacteria; 60 bacteria originally
B) 180 bacteria; $6 \frac { 2 } { 3 }$ bacteria originally
C) 540 bacteria; 20 bacteria originally
D) 180 bacteria; 20 bacteria originally