Correct Answer: B

Rationale: The range is calculated as the difference between the largest and smallest values in a dataset. In this case, the largest number of flights made by the flight attendant in a month was 79, and the smallest number was 54. Therefore, the range is 79 - 54 = 25. Choices A, C, and D are incorrect as they do not reflect the correct calculation of the range based on the given data.

Correct Answer: C

Rationale: To solve this problem, we can set up a system of equations. Let the cost of one container of yogurt be y and the cost of one box of crackers be c. From the first scenario, we have 4y + 3c = 9.55. From the second scenario, we have 2y + 2c = 5.90. Solving these equations simultaneously, we find that c = $2.25. Therefore, one box of crackers costs $2.25. Choice A, $1.75, is incorrect because it does not satisfy the given conditions in the system of equations. Choice B, $2.00, is incorrect as it does not match the calculated solution. Choice D, $2.50, is incorrect as it does not align with the calculated value for one box of crackers.

Correct Answer: B

Rationale: The range is calculated as the difference between the largest and smallest values in a dataset. In this case, the largest number of flights made by the flight attendant in a month was 79, and the smallest number was 54. Therefore, the range is 79 - 54 = 25. Choices A, C, and D are incorrect as they do not reflect the correct calculation of the range based on the given data.

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.

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.