A bacteria culture begins with 15 bacteria which double in amount at the end of every hour. How many bacteria are grown during the 12th hour?

The answer is 30720

A = P * rⁿ

A - the final population

r - the growth rate

P - the initial number of bacteria

n - the number of hours

We know:

A = ?

r = 2 (it doubles)

P = 15

n = 12

After 11 hours

A (11) = 15 * 2¹²

A (11) = 15 * 2048

A (11) = 30720

After 12 hours

A (12) = 15 * 2¹²

A (12) = 15 * 4096

A (12) = 61440

How many bacteria are grown during the 12th hour?

A (12) - A (11) = 61440 - 30720 = 30720