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16. Control group: Subject A

17. Independent (manipulated) variable: Type of powder

18. Dependent variable: Itching time

19. Explain whether the data supports the advertisement´s claims about its product. Yes, it does.

Explanation:

Control group: The control group is used to identify if there are any other factors influencing the results obtained by the treatment in the study (in this case, the new product), from the results that might be a consequence of other factors. The control group must be selected from the same population as the treatment group. Data from an experimental group are compared with the data from a control group. These two groups are identical in all aspects except for the independent variable that the researcher changes in the experimental group to observe how they affect the individuals.  

The experimental group is the one that receives the experimental procedure, with changes in the independent variable.  There can be several experimental groups. In this case, the experimental group is subject B.

Independent (manipulated) variable: Refers to all the variables in an experiment that provoke a response in another variable. An independent variable is the one that changes or is controlled and modified in the experiment to analyze how another variable responds to it. It changes to analyze its effects on the dependent variable. Usually, the independent variable is represented by the X letter. In the exposed example, the type of powder is the independent variable.  Dependent variable: Refers to the variable, which response depends on any change in the independent variable. It represents a quantity of something which value depends on how the independent variable is modified. The change in the dependent variable might be proportional or inversely proportional to the change in the manipulated variable. It is usually identified by the letter Y. In the exposed example, inching time is the dependent variable, that depends on the type of powder used. The data does support the advertisement´s claims about its product. The effect of the new product lasts 50% more than the original product. The old powder produced itching for 30 minutes, while the new product produced itching for 45min (15 more minutes, 50% more).

The speed of  sound:   sound travels  at different speeds depending on what it istraveling through. of the three mediums (gas, liquid, and solid)  sound waves travel the slowest through  gases, faster  through  liquids, and fastest  through  solids.