The formula v=square root of 2.5r models safe maximum speed, v, in miles per hour, at which a car can travel on a curved road with radius of curvature, r, in feet. A highway crew measures the radius of curvature at an exit ramp as 1,000 feet. What is the maximum safe speed?

One of these is the answer, a. 55 mph, b. 100 mph, c. 47 mph or d. 50 mph