The first half of a 400-mile trip was travelled in x hours and the second half in y hours. Which of the following is equal to the average speed, in miles per hour, for the entire trip? Choose the correct choice from the following answers.
A) 200/(x + y) B) 400/(x + y) C) 50/x + 50/y D) 200/x + 200/y E) 100/x + 100/y
Time taken to cover first half i.e 200 miles of a 400 mile trip = x   time taken to cover the second half i.e 200 miles of a 400 mile trip = y   Total time taken = x+y   Average speed for the entire trip =total distance /total time   =400/(x+y)   Answer 400/(x + y)
<result>B</result>
The first half of a 400-mile trip was travelled in x hours and the second half in y hours. Which of the following is equal to the average speed, in miles per hour, for the entire trip?