Correct Answer: A

Rationale: In the study, 60% of 5,000 respondents using smartphones for email would equal 3,000 respondents, not the total number of respondents. Therefore, the correct answer is 3,000 respondents. Choice B, 2,500 respondents, is incorrect because it doesn't consider the percentage of smartphone users. Choice C, 5,000 respondents, is incorrect as it represents the total number of respondents, not the specific number using smartphones for email. Choice D, 1,000 respondents, is incorrect as it is not the correct calculation based on the given information.

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: 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: The correct calculation to determine the medication dosage for a patient weighing 60 kg is: 5 mg/kg x 60 kg = 300 mg. Therefore, the patient should receive 300 mg of medication. Choice A (100 mg) is incorrect as it does not account for the patient's weight. Choice B (150 mg) is incorrect as it miscalculates the dosage. Choice D (400 mg) is incorrect as it overestimates the dosage based on the patient's weight.

Correct Answer: D

Rationale: To calculate the 30% increase, find 30% of 270 mg: 0.30 x 270 mg = 81 mg. Add this increase to the original dosage: 270 mg + 81 mg = 351 mg. Therefore, the patient's dosage after the 30% increase will be 351 mg. Choice A (81 mg) is incorrect as it only represents the calculated increase, not the total dosage post-increase. Choice B (270 mg) is the original dosage and does not account for the 30% increase. Choice C (300 mg) is the original dosage plus 30 mg, not the correct calculation with a 30% increase.