SOLUTION: there's an army 5 miles long marching at 3 mph your in front and you have to take a letter 5 miles to back of the line at 5 mph and return to the front at 5 mph how many miles and

Question 573120: there's an army 5 miles long marching at 3 mph your in front and you have to take a letter 5 miles to back of the line at 5 mph and return to the front at 5 mph how many miles and how many hours did it take
Found 2 solutions by solver91311, Alan3354:
Answer by solver91311(24713) (Show Source): You can put this solution on YOUR website!

When you start, the rear of the army is APPROACHING you at 3 mph and you are traveling 5 mph for a total rate of 8 mph. Using time equals distance divided by rate, it takes you 5/8 of an hour to get to the rear of the column.

On the way back, the front of the army is moving AWAY from you at 3 mph and you are traveling 5 mph for a total rate of 2 mph. T = D/R again, so 5/2 hour to get back to the front.

You can do your own arithmetic.

John

My calculator said it, I believe it, that settles it

Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
there's an army 5 miles long marching at 3 mph your [sic] in front and you have to take a letter 5 miles to back of the line at 5 mph and return to the front at 5 mph how many miles and how many hours did it take
-----------------------
The round trip distance is 10 miles.
----------------
The relative speed going is 3 + 5 = 8 mi/hr
Returning it's 5 - 3 = 2 mi/hr
----
The avg speed for the round trip is
2*8*2/(8 + 2) = 3.2 mi/hr
----
t = d/r = 10/3.2 = 3.125 hours

RELATED QUESTIONS
An army of soldiers is marching down a road at 5 miles per hour. A messenger on horseback (answered by mangopeeler07)
An army, lined up single file, is one mile long. It starts marching at a uniform rate.... (answered by edjones)
an army of soldiers is marching down a road at 5 mph. a messenger on horseback rides from (answered by ankor@dixie-net.com,aajayunlimited,ikleyn)
If a parade is 1 mile long and marching at 3mph How long will it take a jogger at 5mph to (answered by stanbon)
If a parade is 1 mile long and marching at 3mph How long will it take a jogger at 5mph to (answered by ankor@dixie-net.com)
You and your friend are in a canoe race. Your friend is a half mile in front of you and... (answered by richwmiller)
You and your friend are in a canoe race. Your friend is a half mile in front of you and... (answered by josmiceli)
A 1-km long army is in marching order at constant velocity. A corporal from rear end... (answered by ikleyn)
You are going 158mph in Indianapolis which is about 1200 miles west of Dayton, when the... (answered by richwmiller)