OG详解-OG6 数学1 Q4

Choice D is correct. It’s given that during a portion of a flight, a small airplane’s cruising speed varied between 150 miles per hour and 170 miles per hour. It’s also given that s represents the cruising speed, in miles per hour, during this portion of the flight. It follows that the airplane’s cruising speed, in miles per hour, was at least 150, which means s≥ 150, and was at most 170, which means s≤170. Therefore, the inequality that best represents this situation is 150≤s≤ 170.
Choice A is incorrect and may result from conceptual or calculation errors. Choice B is incorrect and may result from conceptual or calculation errors. Choice C is incorrect and may result from conceptual or calculation errors.