Question

question 9
key question | directions: choose 2 scenarios. read and identify the independent & dependent variable, experimental & control group.

scenario | independent variable | dependent variable | experimental group | control group
--- | --- | --- | --- | ---
a company wants to test a new dog food that is supposed to help overweight dogs lose weight. 50 dogs are chosen to get the new food, and 50 more continue their normal diets. after one month, the dogs are checked to see if they lost any weight. | new dog food | dog’s weight | 50 dogs new food | 50 dogs normal diet
a new sunscreen has been developed that is supposed to be more effective at preventing sunburn. 30 participants spray one arm with the new formula, and spray the other arm with the leading formula. after 4 hours in the sun, their skin is evaluated for any redness. | new sunscreen formula | skin redness (sunburn) | arms sprayed with sunscreen formula | arms sprayed with the leading sunscreen formula
a student wants to study the effect of sunlight on plant growth. in his experiment, 12 plants receive normal amounts of sunlight, but half of them are kept under bright sun lamps all night long. after 6 weeks, the plants’ heights are measured. | empty | empty | empty | empty

Explanation:

Scenario 1 (Dog Food Experiment)

• Independent Variable: The factor manipulated (new dog food vs. normal diet).
• Dependent Variable: The outcome measured (weight loss).
• Experimental Group: Group exposed to the independent variable (new food).
• Control Group: Group not exposed to the independent variable (normal diet) for comparison.

Scenario 2 (Sunscreen Experiment)

• Independent Variable: The factor manipulated (new vs. leading sunscreen).
• Dependent Variable: The outcome measured (skin redness from sunburn).
• Experimental Group: Group exposed to the new sunscreen.
• Control Group: Group exposed to the standard (leading) sunscreen for comparison.

Scenario 3 (Plant Growth & Sunlight Experiment)

• Independent Variable: The factor manipulated (extra sunlight via lamps vs. normal sunlight).
• Dependent Variable: The outcome measured (plant height after 6 weeks).
• Experimental Group: Group exposed to the manipulated sunlight (lamps at night).
• Control Group: Group with normal sunlight for comparison.

Answer:

• Independent Variable: New Dog Food
• Dependent Variable: Dog’s weight
• Experimental Group: 50 dogs with new food
• Control Group: 50 dogs with normal diet