Question

a student wants to shorten the ripening time for tomatoes. he predicts that the more water the seedlings receive, the faster the tomatoes will ripen. he grows 20 tomato plants in a garden in full sunlight that has dry soil, and 20 tomato plants in the same garden where there is more moisture in the soil. he records the time it takes for fruit to develop and ripen on the plants in each location.
what is the independent variable in this experiment?

• the time it takes for the fruit to develop and ripen.
• the tomato seedlings at different stages of development.
• the amount of sunlight each plant receives.
• the amount of water each plant receives.

Explanation:

To determine the independent variable, we recall that the independent variable is the factor manipulated by the experimenter. Here, the student predicts the effect of water on ripening time. So the amount of water each plant receives is what's being changed (manipulated) to observe its effect on ripening time. The other options: time to ripen is the dependent variable (measured), tomato seedlings' stages aren't the focus, and sunlight isn't the manipulated factor here (the garden is in full sunlight, so sunlight is constant).

Answer:

The amount of water each plant receives