Answer:
Independent variable: washer detergent
Dependent varaible: cleaing power of effectivenes of the detergent.
Step-by-step explanation:
When an experiiment is performed there exists one independent variable, one dependent variable, and some other variables that must be controlled.
The goal of the experiment is to test a hypothesis, which is a statement that relates an effect with a cause and that must be proved true or false.
The effect in the dependent variable, and the cause is the independent variable.
Jenny (the scientist) wants to show how an effect or phenomenun, the dependent variable, is explained by the explanatory, independent, variable.
In the stated experiment, Jenny wants to know how the effectiveness of a new brand detergent and an old one compare with each other. Therefore, she designs a test in which she will determine how the brand of detergent may explain (explanatory or independent variable) the cleaning power or effectiveness, the dependent variable.
Jenny only can manipulate the independent variable and observe the effect on the dependent variable.
To be conclusive, other variables must be controlled, like the fabric and the amount of dirt of the t-shirts.