A certain exam has 30 questions. A student gets 1 point for each question answered correctly and loses half a point for each question answered incorrectly; no points are gained or lost for questions left blank. If x represents the number of questions a student answers correctly and y represents the number of questions left blank, which of the following expressions represents the student's score on the exam?

Correct Answer: A

Rationale: The student's score is calculated by adding the points earned for correct answers (x) and subtracting the points lost for incorrect answers (y/2). Therefore, the expression for the student's score on the exam is x - y/2. Option A is correct because it accurately represents this calculation. Option B (x - y) is incorrect as it does not account for the penalty of losing half a point for each incorrect answer. Option C (30 - (x + y)) is incorrect as it subtracts the total number of questions from the sum of correct and blank answers, which does not represent the scoring system. Option D (30 - x - y/2) is also incorrect as it incorrectly subtracts x from 30 and then deducts y divided by 2, which is not the correct scoring method for the exam.

Correct Answer: C

Rationale: The equation y = 40x represents John's Gym charging $40 per month, while the equation y = 45x represents Ralph's Recreation Room charging $45 per month. Since $40 is less than $45, it can be concluded that John's Gym offers a lower monthly membership fee compared to Ralph's Recreation Room. Therefore, the correct answer is that John's monthly membership fee is less than Ralph's monthly membership fee. Choices A and B are incorrect because John's fee is not equal to or greater than Ralph's fee. Choice D is incorrect as there is a clear relationship indicating that John's monthly membership fee is less than Ralph's monthly membership fee.

Correct Answer: D

Rationale: The scale of 1:100 means that 1 cm² on the floor plan represents 100 cm² in real life. To find the actual area of the room, you need to multiply the area on the floor plan by the square of the scale factor. Since the scale is 1:100, the scale factor is 100. Therefore, 50 cm² on the floor plan represents 50 * 100 = 5000 cm² in real life. Choice A (500 m²) is incorrect as it converts the area from cm² to m² without considering the scale factor. Choice B (50 m²) is incorrect as it does not account for the scale factor. Choice C (5000 cm²) is incorrect as it gives the area on the floor plan, not the actual area.

Correct Answer: D

Rationale: A pie chart is the most appropriate choice for displaying the percentages of time spent on different tasks during the workday because it visually represents parts of a whole. In this case, each task's percentage represents a part of the entire workday, making a pie chart an ideal way to compare these percentages. Line plots, bar graphs, and line graphs are not suitable for showing percentages of a whole; they are more commonly used for tracking trends, comparing values, or showing relationships between variables but do not efficiently represent parts of a whole like a pie chart does.

Correct Answer: A

Rationale: To solve the equation 3(x - 5) = 2(x + 3) for x, start by distributing the terms inside the parentheses. This gives you 3x - 15 = 2x + 6. Next, combine like terms by moving all terms with x to one side and the constants to the other side. Subtracting 2x from both sides gives x - 15 = 6. Finally, adding 15 to both sides results in x = 21. Therefore, the correct answer is A: x = 3. Choices B, C, and D are incorrect as they do not result from the correct calculations of the equation.