Correct Answer: D

Rationale: To convert a decimal to a percentage, you multiply by 100. Therefore, to find the percentage equivalent of 0.0016, you would multiply 0.0016 by 100 to get 0.16%. This means that choice D, '0.16%', is the correct answer. Choices A, B, and C are incorrect because they do not correctly represent the percentage equivalent of 0.0016.

Correct Answer: C

Rationale: The range in the number of houses sold per year is calculated by subtracting the minimum number of houses sold from the maximum number of houses sold. In this case, the range is 42 (maximum) - 11 (minimum) = 31, not 29 as stated in the original rationale. Therefore, choice C (29) is incorrect. Choices A (20), B (25), and D (35) are also incorrect as they do not reflect the correct range of houses sold per year, which is 31.

Correct Answer: B

Rationale: To calculate a 20% decrease of 400 mg, you multiply 400 mg by 0.20 to get 80 mg. Subtracting 80 mg from the current dosage of 400 mg results in a new dosage of 320 mg. Choice A is incorrect because it miscalculates the decrease. Choice C is incorrect as it represents a 20% increase instead of a decrease. Choice D is incorrect as it represents the initial dosage, not the reduced dosage.

Correct Answer: C

Rationale: To find the fraction of the class wanting to work with the elderly, we convert the percentage to a fraction. 60% can be written as 60/100, which simplifies to 3/5. Therefore, 3/5 of the class wanted to work with the elderly. Choice A (1/4), choice B (1/10), and choice D (1/20) do not represent the fraction of the class wanting to work with the elderly, making them incorrect.

Correct Answer: C

Rationale: To determine the highest percentage, we need to calculate each option. The percentage in answer A is: 50 / 250 x 100 = 20%. The percentage in answer B is: 57 / 250 x 100 = 22.8%. The percentage in answer C is: (74 + 55) / 433 x 100 = 29.8%. The percentage in answer D is: 21 / 183 x 100 = 11.5%. Therefore, the correct answer is C, as it has the highest percentage of doctors among the staff at both hospitals. Choices A, B, and D are incorrect as they have lower percentages compared to choice C.