Sarah wants to know which brand of nail polish lasts the longest without chipping. She buys 4 types of nail polish – Essie (which she normally uses,) Butter, OPI, and Sally Hansen. Every Sunday for 4 weeks she paints her nails with a different brand of polish and records how many days she lasts before she gets her first chip. She makes sure to use the same bottom coat and top coat with each type of polish, and she makes sure to do the same weekly routine each week so that her nails aren’t getting treated more roughly different weeks.

This is an example of scientific investigation and all the elements that compose it.

Explanation:

Sarah is doing a scientific investigation regarding the nail polishes she uses. We can see this, because Sarah is using the elements that make up this type of investigation to reach a conclusion about the enamels. These elements are:

Independent variable: Element that influences the appearance of a controlled and evaluable result, such as the enamel that Sarah will use on her nails.

Dependent variable: Element that is influenced by the dependent variable and promotes the visualization of a result, such as the length of time that the enamels can remain on the nail without chipping.

Experimental group: Element that allows the study of the interaction of these variables and the result developed through it, such as Sarah's enamel marks.

Control group: Element where only the independent variable is applied. As the action of the dependent variable does not exist, the observed result is the same that would be perceived if the study was not taking place, such as the day when Sarah did not paint her nails.

Constant: Elements that are exactly the same throughout the experiment, such as the person who conducted it, the time the study will be carried out, the nail care routine and the lower and upper layers of the enamels used.

answer: 21

step-by-step explanation:

divide 630 by 30. 30 goes into 630 21 times