Correct Answer: D

Rationale: When rolling a standard six-sided die, there are three even numbers (2, 4, 6) out of a total of six possible outcomes (1, 2, 3, 4, 5, 6). The probability of rolling an even number can be calculated as the number of favorable outcomes (3) divided by the total number of outcomes (6), which equals 3/6 = 50%. Therefore, the correct answer is D. Choice A (16%) is incorrect because it does not represent the probability of rolling an even number. Choice B (33%) is incorrect as it does not reflect the correct probability. Choice C (66%) is incorrect as well since it overestimates the probability.

Correct Answer: B

Rationale: To find the sum of fractions with the same denominator, add the numerators. Here, 3/7 + 4/7 + 2/7 = (3 + 4 + 2)/7 = 9/7. Therefore, the correct answer is 9/7. Choice A (7/7) is incorrect as the sum is not 7/7. Choice C (6/7) is incorrect as the sum is not 6/7. Choice D (7/7) is incorrect as the sum is not 7/7.

Correct Answer: A

Rationale: To subtract mixed numbers, find a common denominator. Converting 6 1/2 to 6 3/6 and 2 2/3 to 2 4/6, the calculation becomes 6 3/6 - 2 4/6 = 4 1/6. Therefore, the correct answer is A. Choice B (3 1/3) is incorrect as the correct result is not an improper fraction. Choice C (3 5/6) is incorrect as it does not represent the result of the subtraction. Choice D (4 1/3) is incorrect as it does not match the correct calculation.

Correct Answer: B

Rationale: 1 gram is equivalent to 1000 milligrams. The concentration of the medication is 200 milligrams per milliliter. To calculate the volume needed, divide the total amount of medication by the concentration: 1000 mg / 200 mg/mL = 5 mL. Therefore, 5 milliliters of the solution should be drawn up to administer 1 gram of the medication intravenously. Choice A (4 milliliters), Choice C (10 milliliters), and Choice D (20 milliliters) are incorrect because they do not accurately calculate the volume of the solution needed based on the concentration of the medication.

Correct Answer: A

Rationale: To subtract mixed numbers, find a common denominator. Convert 28 3/4 to 28 9/12. Then, subtract 5 5/6 from 28 9/12 to get 22 11/12. Therefore, 28 3/4 - 5 5/6 = 22 & 11/12, which matches choice A. Choices B, C, and D are incorrect because they do not reflect the correct subtraction result after finding the common denominator and performing the subtraction.