Two methods are proposed to measure the effectiveness of a brand of sunscreen. Method A: Survey adults visiting a beach on a busy weekend. Ask each adult which brand of sunscreen they are using, and assess their arms for sun exposure.

Method B: Volunteers are randomly assigned to one of two brands of sunscreen. Each volunteer is asked to report back at the end of the day, and their arms are assessed for sun exposure.

Which statement is a correct interpretation of these methods?

Both methods are experiments because sun exposure is assessed in both methods.
Both methods are observational studies because neither method attempts to influence responses.
Method A is an experiment because it compares many brands of sunscreen, while method B is an observational study.
Method B is an experiment because it randomly assigns volunteers a sunscreen, while method A is an observational study.

Method B is an experiment because it randomly assigns volunteers a sunscreen, while method A is an observational study.

Step-by-step explanation:

Based on the information given, we can infer that method A is an observational study. An observational study simply refers to the study whereby the researchers just observe the impact of a rise factor without them trying to change the people or things exposed to it. This can be seen as the survey adults visited the beach on the busy weekend asking each adult the brand of sunscreen that they use and then assess their arms for sun exposure.

Method B is an experiment. An experiment refers to a test that's carried out in order to evaluate a particular hypothesis or theory. Method B is an experiment because it randomly assigns volunteers a sunscreen.

Therefore, the correct option is D.

d, x=8

step-by-step explanation:

simplifying

4x + -5 = 2x + 11

reorder the terms:

-5 + 4x = 2x + 11

reorder the terms:

-5 + 4x = 11 + 2x

solving

-5 + 4x = 11 + 2x

solving for variable 'x'.

move all terms containing x to the left, all other terms to the right.

add '-2x' to each side of the equation.

-5 + 4x + -2x = 11 + 2x + -2x

combine like terms: 4x + -2x = 2x

-5 + 2x = 11 + 2x + -2x

combine like terms: 2x + -2x = 0

-5 + 2x = 11 + 0

-5 + 2x = 11

add '5' to each side of the equation.

-5 + 5 + 2x = 11 + 5

combine like terms: -5 + 5 = 0

0 + 2x = 11 + 5

2x = 11 + 5

combine like terms: 11 + 5 = 16

2x = 16

divide each side by '2'.