Chapter 11 - Section 11.1 - Sequences - Exercise Set - Page 639: 40

Size of the culture at the beginning of the fourth hour $=1350$ Size of the culture at the beginning of the first hour $=50$

$a_{n}=50(3)^{n-1}$ Size of the culture at the beginning of the fourth hour $a_{4}=50(3)^{4-1}$ $a_{4}=50(3)^{3}$ $a_{4}=50(27)$ $a_{4}=1350$ Size of the culture at the beginning of the first hour $a_{1}=50(3)^{1-1}$ $a_{1}=50(3)^{0}$ $a_{1}=50(1)$ $a_{1}=50$