The distance from City A to City B is 120 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?	Answers
A) 45 B) 48 C) 50 D) 52 E) 54
The time it takes Bob to drive to City B is 120 / 40= 
<gadget id="calculator">120 / 40</gadget>
<output>3</output>
3 hours.   Alice needs to take less than 2.5 hours for the trip.   Alice needs to exceed a constant speed of 120 / 2.5= 
<gadget id="calculator">120 / 2.5</gadget>
<output>48</output>
48 miles per hour.   The answer is 48.
<result>B</result>
The distance from City A to City B is 120 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?