Answer: the speed of the elevator is 4.6 miles per hour.
Explanation:
Given, The elevator in the Washington Monument takes 75 seconds to travel 506 feet to the top floor. 
Since 1 hour = 3600 seconds
⇒ 1 second = 
 hour
 hour
⇒ 75 seconds = 
 hour
 hour 
 hour
 hour
1 mile = 5280 feet
1 feet = 
 mile
 mile
506 feet = 
 miles
 miles 
 miles
 miles
Speed = 


Hence, the speed of the elevator is 4.6 miles per hour.