Section: Arithmetic Reasoning

1) Richard drives from his home to work at an average speed of 50 miles per hour. Later he drives from his work to home at a speed of 60 miles per hour. What is his average speed over the two trips?

1. 54.5 miles per hour
2. 55 miles per hour
3. 55.5 miles per hour
4. 56 miles per hour

You may assume the answer is to take the average of the two journeys, which would require adding 50 plus 60 and dividing by 2. However, if a person is going at a slower speed then it takes more hours so the answer will be close to the lower speed. The best way to solve this is to setup a destination length and solve for x, which is the average speed. Assume the destination length is 300 miles.

300/50 = 6 hours and 300/60 = 5 hours. Therefore it takes 11 hours to travel the entire distance of 600 miles. 600/11 = 54.5 miles per hour.