A microbiologist inoculated a flask of nutrient broth with E. coli. The bacterial population entered exponential phase at 11:30 pm and divided every 60 min. At 6:30 am, the culture entered stationary phase with a population of 100,000,000 bacteria mL-¹. At what time was the population 50,000,000 bacteria mL-¹? 5:30 am 12:30 am 4:30 am O Can not be determined from the information given. 3:30 am

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