Mathematics > Standard Multiple Choice

Read the following SAT test question and then click on a button to select your answer.

A woman drove to work at an average speed of 40 miles per hour and returned along the same route at 30 miles per hour. If her total traveling time was 1 hour, what was the total number of miles in the round trip? 

(A) 30
(B) 
(C) 
(D) 35
(E) 40

答案请点击下一页>>>

The Correct answer is C.

Explanation

Let  represent the time it took the woman to drive to work. Since her total traveling time was  hour, the time it took her to return home is . The distance in miles can be found using the formula . The distance traveled to work is , and the return distance is . Since the distance to work is the same as the return distance, . Solving for  yields . So the distance one way is  miles. The total number of miles in the round trip is , or  miles.