Correct Answer: B

Rationale: To calculate the amount saved from the original price, you need to subtract the discounted price from the original price. The formula is: Original price - Discounted price = Amount saved. In this case, the original price was $850, and the discounted price was $637.50. Therefore, $850 - $637.50 = $212.50. Hence, he saved $212.50 from the original price. Choice A ($170) is incorrect as it is not the correct amount saved. Choice C ($105.75) is incorrect as it does not match the calculated savings. Choice D ($200) is incorrect as it is not the accurate amount saved based on the given prices.

Correct Answer: A

Rationale: To find the percentage of Dr. Lee's patients hospitalized, you need to calculate 5% of the 30% who developed an infection. 5% of 30% is 1.5%. Therefore, 1.5% of Dr. Lee's patients were hospitalized. Choice A is correct. Choices B, C, and D are incorrect because they do not accurately reflect the calculation of the percentage of patients requiring hospitalization after taking the antibiotic.

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: 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: B

Rationale: To determine the number with the greatest value among the options, focus on the digit in the tenths place. In this case, 1.07548 has the highest value as it has the digit 7 in the tenths place. Comparing this to the other numbers, 1.4378, 1.43592, and 0.89409 have 4, 3, and 8 in the tenths place, respectively. Therefore, 1.07548 is the number with the greatest value as it has the highest digit in the tenths place.