A cyclist bikes x distance at 10 miles per hour and returns over the same path at 8 miles per hour. What is the cyclist’s average rate for the round trip in miles per hour?
2006-12-07 16:54:39 · 7 answers · asked by dfsd s 1 in Science & Mathematics ➔ Chemistry
Say he went 40 miles. Then the first leg he would take 4 hours. The return would take 5 hours.
Total distance is 80 miles. He took 9 hours.
D=rt so r= distance/time = 80/9 = 8.88 mph
2006-12-07 16:58:49 · answer #1 · answered by ignoramus 7 · 0⤊ 0⤋
The outward trip takes x/10 hours and the return trip takes x/8 hours. The total time taken to travel distance 2x is x/10 + x/8.
x/10 + x/8 = (8x + 10x)/80 = 18x/80
So average speed is 2x divided by 18x/80 = 160x/18x = 160/18 = 8.89 miles/hr. Note that it is NOT 9 miles/hr as the two trips take different lengths of time.
2006-12-08 01:48:28 · answer #2 · answered by Martin 5 · 0⤊ 0⤋
He travelled 18 miles in 2 hours so divide 18 miles by 2 hrs = 9mph. If he travelled 18 miles in 3 hrs = 6mph. 18 miles in one hour = 18mph. Speed equals distance divided by time ! Time equals distance divided by speed, and distance equals speed times time ! There was a special triangle we used in school ! D/SxT
2006-12-11 15:14:25 · answer #3 · answered by bobsterjay 1 · 0⤊ 0⤋
as the distance is same so
average speee = (10+8)/2
ie. 9 miles per hour
2006-12-08 01:06:04 · answer #4 · answered by usman 3 · 0⤊ 0⤋
The question is incomplete, you need the value of time to answer this
2006-12-08 00:58:30 · answer #5 · answered by hezrongibe 1 · 0⤊ 0⤋
Chemistry? Chemistry? I still despair!
2006-12-08 01:37:33 · answer #6 · answered by checkmate 6 · 0⤊ 0⤋
nine
2006-12-08 00:59:35 · answer #7 · answered by iwondersoiask 4 · 0⤊ 0⤋