The distance from City A to City B is 180 miles. While driving from City A to City B, Bob drives at a constant speed of 40 miles per hour. Alice leaves City A 30 minutes after Bob. What is the minimum constant speed in miles per hour that Alice must exceed in order to arrive in City B before Bob?
Pick one: A) 45 B) 48 C) 50 D) 52 E) 54

Rationale: "the time it takes bob to drive to city b is 180 / 40 = 4.5 hours . alice needs to take less than 4 hours for the trip . alice needs to exceed a constant speed of 180 / 4 = 45 miles per hour . the answer is a ."
Answer: A