Hello!
A likely hypothesis to the question "Do fertilizers make plants grow faster?" is: If we fertilize a plant, then its height increases faster.
A hypothesis is a supposition made from data that is the basis for an investigation. The hypothesis formulates the central question of the investigation in an affirmative way. In this case, the affirmation that is the most similar to the question is If we fertilize a plant, then its height increases faster.
Also, a hypothesis should be written in a way that it can be proved through an experiment. In this case, an experiment can be designed from the hypothesis, measuring the height of the plants when adding fertilizer and when not, to test the hypothesis. This is called falsifiability.
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