A culture of bacterial triples in size every four hours. If the bacteria population is estimated to be three million now, what will it be one day from now? A. 243,000,000 B. 2,187,000,000 C. 6,561,000,000 D. 4,238,000,000

It triples in size every 4 hours, so in 24 hours, there will be 6 triplings.

3 ^ 6 = 729

So, in 24 hours, the population will increase by a factor of 729.

The population will be 729 * 3 million = 2,187 billion.

The answer is B.