Question

directions: ... identify the independent variable, dependent variable, and the control. beware- not all experiments will have a control!

1. sara wants to see if a new brand of hair dye lasts longer than the brand she currently uses. she puts the new hair dye on the left side of her head and the old brand on her right side. after 2 weeks she observes which side of her head has more gray hair showing through.

a. independent variable =
b. dependent variable =
c. control =

1. rob is in charge of waxing the floor at the local mall. he wants to test a new brand of floor wax called squeaky clean. rob waxes 20 floor tiles with squeaky clean and 20 tiles with the original wax brand. after one week he counts the number of scratches on the floor.

a. independent variable =
b. dependent variable =
c. control =

1. chris wants to see if his basil plants grow better in full sunlight or partial sunlight. he plants 5 basil plants on the east side of his house that only receives light in the morning, and 5 more plants on the south side of his house that receives light all day. after a month chris measures the height of each plant.

a. independent variable =
b. dependent variable =
c. control =

1. shannon wants to see if the amount of time she studies will affect her grades. she normally studies for 30 minutes a night, but decides to double her study time to one hour per night. over the next three weeks shannon sees her science grade raise 10%.

a. independent variable =
b. dependent variable =
c. control =

Explanation:

Problem 1:

• Independent Variable: The factor that is changed or manipulated. Here, the new brand of hair dye (since Sara is testing if it lasts longer, she changes the brand).
• Dependent Variable: The factor that is measured or observed. The length of time the dye lasts (or the number of gray hairs showing, as she observes which side has more gray) depends on the brand of dye.
• Control: The old brand of hair dye (the original brand she used, to compare with the new one).

• Independent Variable: The factor manipulated. Here, the brand of floor wax (Squeaky Clean vs original).
• Dependent Variable: The factor measured. The number of scratches on the floor depends on the wax brand.
• Control: The original wax brand (used to compare with the new one).

• Independent Variable: The factor manipulated. The amount of sunlight (full vs partial) the basil plants receive.
• Dependent Variable: The factor measured. The height of the basil plants depends on the sunlight.
• Control: There isn't a traditional control here, but if we consider, maybe the plants with consistent light (but since he has two groups, full and partial, the control could be a standard or the initial state, but more accurately, the independent variable is sunlight, dependent is plant height, and control might be a group with normal light, but from the problem, he has east (full) and south (partial) – maybe the control is not clearly defined, but based on the problem, we identify variables.

Answer:

a. Independent Variable = Brand of hair dye (new vs old)
b. Dependent Variable = Number of gray hairs showing (or length of time dye lasts)
c. Control = Old brand of hair dye

Problem 2: