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

13 * 3 ^n-1
13*3^10-1
13*3^9
13*19683
255879
C is your answer

Answer 2

Answer: C) 255879

Explanation:

Since, the initial number of bacteria = 13,

Thus, if the bacteria is tripled in one hour,

Then the number of bacteria after one hour = 13

In second hour = 13 ×3 =
`13(3^(2-1))`

In third hour = 13 × 3 × 3 =
`13(3^(3-1))`

In fourth hour = 13 × 3 × 3 × 3 =
`13(3^(4-1))`

Similarly, in 10th hour the number of bacteria

=
`13(3^(10-1))`

=
`13(3^9)`

=
`13* 19683`

=
`255879`

Hence, the number of bacteria in 10th hour = 255879

⇒ Option C is correct.