A person covered one-fourth of the total distance at 20 kmph and remaining distance at 24 kmph. What is the average speed for the total distance?	Select the correct option
A) 21 (1/8)  B) 21 (1/7)  C) 22 (6/7)  D) 29 (1/7)  E) 21 (4/3)
Let the total distance be x km   total time taken = (x/4)/20 + (3x/4)/24 = 7x/160   Average speed = x/(7x/160) = 22 (6/7)kmph.   Answer: 22 (6/7)
<result>C</result>
A person covered one-fourth of the total distance at 20 kmph and remaining distance at 24 kmph. What is the average speed for the total distance?