Question

A certain species of virulent bacteria is being grown in a culture. It is observed that the rate of growth of the bacterial population is proportional to the number present. If there were 1000 bacteria in the initial polulation and the number doubled after the first 30 minutes, how many bacteria will be present after 4 hours

Answer 1

256,000

Explanation:

If the culture doubles in size every 30 minutes, it doubles 2 times per hour. In 4 hours it will have doubled 2×4 = 8 times. Each doubling multiplies the number by 2, so 8 doublings will multiply the number by 2^8.

The population will be ...

1000×2^8 = 256,000 . . . bacteria present after 4 hours