Answer:
250
Step-by-step explanation:
According to the question the number of bacteria population becomes double in 9 hours to that of 1 hr that means bacteria is dividing in 9 hours. Each time the bacteria divides, the numbers become double.
As we have found that bacteria is dividing in 9 hours so for the first 9 hours the number will be same as initial population i.e. 250. But just after nine hours the population will be double i.e. 500.
So, after 3 hours the population will be same as initial population, 250.