A population of bacteria doubles every 15 hours. Initially, the population of bacteria is 40. What is the population of the bacteria after 40 hours? Enter your answer, rounded to the nearest whole number, in the box.

A number of bacteria after 30 hours is 480 bacteria.

The answer is 480 because originally the amount was 80. After 12 hours it doubled to 160. Then after 24 hours have passed, the amount doubled again. So now the amount is 320 bacteria. Then 6 hours passed (half of 12 hours) so then you add half of that amount (160) to 320. 320 plus 160 is 480. So the answer is 48