Answer:
Number of independent variables = 2
Step-by-step explanation:
Lets stary with definitions. First of all, variables are properties, of an experiment that take on different amounts or values, rather than a constant that has one unchanging value assigned to it.
Now, we have two kinds of variables namely dependent and independent variables. For this question, we need to know independent variables. Independent variables are variables that could be manipulated at discretion. In the question, the independent variable is "the size of breakfast" because the experimenter chose by reason of choice to either use 350-calories or 750- calories breakfast.
However, the dependent variables are those whose outcomes are with respect to the change in the independent variable. The experiment is actually out to observe how the dependent variable plays out during the experiment. In our example, the dependent variable is "overall food consumption throughout the rest of the day". Thus, the outcome of the overall food consumption throughout the rest of the day is as a result of the size of breakfast taken.
Now, the independent variable can take on various levels, and the number of levels are the number of experimental conditions that the independent variables can take. In our example the independent variable (size of breakfast), was either 350-calories breakfast or 750-calories breakfast, hence it took 2 experimental conditions.
Thus, we say that number of independent variables is 2.
