sat suite question viewer
The number of bacteria in a liquid medium doubles every day. There are bacteria in the liquid medium at the start of an observation. Which represents the number of bacteria, , in the liquid medium days after the start of the observation?
Explanation
Choice D is correct. Since the number of bacteria doubles every day, the relationship between and can be represented by an exponential equation of the form , where is the number of bacteria at the start of the observation and the number of bacteria increases by a factor of every day. It’s given that there are bacteria at the start of the observation. Therefore, . It’s also given that the number of bacteria doubles, or increases by a factor of , every day. Therefore, . Substituting for and for in the equation yields .
Choice A is incorrect and may result from conceptual or calculation errors.
Choice B is incorrect and may result from conceptual or calculation errors.
Choice C is incorrect. This equation represents a situation where the number of bacteria is decreasing by half, not doubling, every day.