Correct Answer: B

Rationale: The correct answer is B: 'The grades students received.' In this scenario, the grades students received are the dependent variable because they are influenced by the number of hours spent studying. The grades are the outcome that is being measured based on the manipulation or observation of the independent variable, which in this case is the number of hours spent studying. Choices A, C, and D are incorrect. The number of hours spent studying is the independent variable being manipulated or observed, the subjects students studied is not directly related to the dependent variable, and the number of students in the study is not the variable being measured or influenced by the independent variable.

Correct Answer: C

Rationale: To find the perimeter of a hexagonal field with 6 sides, multiply the length of one side (320 feet) by the number of sides (6): 320 x 6 = 1920 feet. The total cost of the fencing material can be calculated by multiplying the perimeter by the cost per foot: 1920 feet x $1.75 = $3360. Therefore, the farmer will need to spend $3,360 on fencing material to enclose the perimeter of the field. Choice A, B, and D are incorrect as they do not accurately calculate the total cost based on the given measurements and cost per foot.

Correct Answer: B

Rationale: To simplify the expression, first find a common denominator for the fractions. 3/22 can be rewritten as 6/22. Now, the expression becomes 13/22 - 6/22 - 11. Subtracting 6/22 from 13/22 gives 7/22. Therefore, the correct answer is 7/22. Choice A, 19/22, is incorrect as the subtraction was not done properly. Choices C and D are incorrect as they are not part of the expression being simplified.

Correct Answer: C

Rationale: To calculate the average of Pernell's scores, add all the scores together and then divide by the number of scores. (81 + 92 + 87 + 89 + 94) = 443. Now, divide 443 by 5: 443 · 5 = 89, which is the average score.

Correct Answer: A

Rationale: The correct answer is A: 1/2. When flipping a fair coin, there are two possible outcomes: heads or tails. The probability of getting heads is 1 out of 2 possible outcomes, which can be expressed as 1/2. Choice B, 1/3, is incorrect because a fair coin only has two sides. Choices C and D, 1/4 and 1/5, are also incorrect as they do not represent the correct probability of getting heads when flipping a coin.