Correct Answer: B

Rationale: To find the median of a set of numbers, first arrange the scores in ascending order: 78, 83, 92, 97. Since there is an even number of scores, we find the median by taking the average of the two middle values. In this case, the middle values are 83 and 92. Calculating (83 + 92) / 2 = 85, we determine that the overall median of Dwayne's scores is 85. Choice A (19) is incorrect as it does not correspond to any value in the given set of scores. Choice C (83) is the median of the original set but not the overall median once arranged. Choice D (87.5) is the average of all scores but not the median.

Correct Answer: B

Rationale: To find the median of a set of numbers, first arrange the scores in ascending order: 78, 83, 92, 97. Since there is an even number of scores, we find the median by taking the average of the two middle values. In this case, the middle values are 83 and 92. Calculating (83 + 92) / 2 = 85, we determine that the overall median of Dwayne's scores is 85. Choice A (19) is incorrect as it does not correspond to any value in the given set of scores. Choice C (83) is the median of the original set but not the overall median once arranged. Choice D (87.5) is the average of all scores but not the median.

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: A

Rationale: To simplify the given expression, multiply the numerators together and the denominators together. 5/9 15/36 = (5 15) / (9 36) = 75 / 324. Now, simplify the resulting fraction by finding the greatest common divisor (GCD) of 75 and 324, which is 3. Divide both the numerator and denominator by 3 to get the simplified fraction: 75 · 3 / 324 · 3 = 25 / 108. Therefore, the simplified form of 5/9 15/36 is 25/108, which is equivalent to 5/36. Choice A, 5/36, is the correct answer. Choice B, 8/27, is incorrect as it does not match the simplified form of the expression. Choice C, 10/17, is unrelated and does not result from the given multiplication. Choice D, 15/27, does not correspond to the simplification of the given expression.

Correct Answer: B

Rationale: The total number of faculty members is 15 teachers + 20 teaching assistants = 35. The ratio of faculty to students is then 35:200, which simplifies to 7:40. Further simplifying by dividing both numbers by 5 gives the ratio 4:20, which can be simplified to 4:17. Therefore, the correct ratio is 4:17. Choices A, C, and D are incorrect ratios and do not match the calculated ratio of faculty members to students in this scenario.