Eric is driving a car in which the speedometer is calibrated in kilometers per hour (kph). He notes that his car is traveling at a rate of 75 kph, when he passes a speed limit sign stating the limit is 40 miles per hour (mph). He knows that a kilometer is about 5/8 of a mile. If a police officer stops him at this point, how many mph over the limit will the ticket read?
A kilometer is 5/8 of a mile, so multiply 75 × 5/8, or 75/1 × 5/8 = 375/8. Divide 8 into 375 to reduce the fraction and determine that Eric was traveling at 47 miles per hour, 7 mph over the 40 mph posted limit.