Question

every day at work, tracy poured a large cup of tea that she drank throughout the morning. she wondered how much bacteria might be growing in her cup of tea as the morning went on. to find out, tracy filled three identical cups with tea and placed them on her desk for three hours. after the first hour, she placed a drop of the tea from each cup on a separate microscope slide and counted the number of bacteria in the drop. tracy repeated this with each cup of tea after the second hour, and again after the third hour. complete the sentence. in this experiment, the amount of time that the tea sat on the desk was a dependent variable an independent variable

Explanation:

The independent variable is the factor that the experimenter manipulates or changes. Here, Tracy controls the time the tea sits on the desk (1 - hour intervals for 3 hours). The amount of bacteria (dependent variable) is expected to change based on this time - factor.

Answer:

an independent variable