Question

A bacteria culture begins with 13 bacteria which triple in amount at the end of every hour. How many bacteria are grown during the 10th hour?

A. 13,312

B. 26,624

C. 255,879

D. 2,302,911

Answer 1

The end of first hour = 13*3 = 39

The end of second hour = 39*3 = 117

The end of third hour = 117*3 = 351

The end of fourth hour = 351*3 = 1,053

The end of fourth hour = 1053*3 = 3,159

The end of fifth hour = 3159*3 = 9,477

The end of sixth hour = 9477*3 = 28,431

The end of seventh hour = 28341*3 = 85,293

The end of eighth hour = 85293*3 = 255,879

The end of ninth hour = 255879*3 = 767,637

The end of tenth hour = 767637*3 = 2,302,911

The correct answer is D.2,302,911

Answer 2

Answer:

255,879

Geometric Sequence Formula

`a_n = a1r^((n-1))\\\\a_1 :13\\\\r:3\\\\n:10\\`

Steps:

`a_1_0=13 (3)^((10-1))\\\\a_1_0=13(3)^((9))\\\\a_1_0=(13)19683\\\\a_1_0=255,879`