I drive from St. Louis to Chicago at 40 miles an hour. Upon arrival, I instantaneously return to St. Louis, driving 50 miles an hour.
The first correct answer with a brief explanation will be deemed "best."
2006-11-06 11:38:26 · 12 answers · asked by topher8128 2 in Science & Mathematics ➔ Mathematics
I missed the question part: What is my average speed?
2006-11-06 11:39:04 · update #1
Thanks to Malcolm, who has submitted the best answer, and will be designated as such when Yahoo lets me.
2006-11-06 11:58:10 · update #2
44.44444 mph. If the distance of one leg is x miles, then you drove a total of 2x miles in (x/40 + x/50) hours. Divide the total distance driven by the total time spent driving, and you get 200/9, or 44.444... mph
2006-11-06 11:48:01 · answer #1 · answered by Malcolm 1 · 2⤊ 0⤋
time = distance/rate
time to get to Chicago=x/40 where x is the number of miles between Chicago and St. Louis.
Time to get back to St. Louis= x/50.
Therefore, the total time is x/40+x/50=x(1/40+1/50)
= x*(9/200)
Since rate equals distance divided by time, for the round trip, rate=2x/(9x/200)=400/9=44.44 mph as an average speed.
2006-11-06 19:50:41 · answer #2 · answered by bruinfan 7 · 1⤊ 1⤋
It is NOT 45. It is less.
d = distance between cities
time1 = d/40
time2 = d/50
avg speed = 2d/(d/40+d/50) = 2/(1/40+1/50) = 400/9= 44.44
This is known as the harmonic avg (always smaller than the arithmetic avg).
2006-11-06 19:55:14 · answer #3 · answered by Anonymous · 0⤊ 1⤋
It takes X/40 mph in the first case and in the second case it is X/50 mph.
The total time for the two journeys :
X/40 + X/50= 0.02 + 0.025= 0.045X hours.
The total distance is 2X We divide 2X by the time to get the speed.
2X /0.045 = 44.44 mph
So 44.4444 is the correct answer. What prize do I win?
2006-11-06 19:55:10 · answer #4 · answered by Sam P 2 · 0⤊ 1⤋
I looked up the distance, which is 294 miles.
Averaging 40 mph, it will take 7.35 hours to get to Chicago. On the way back, averaging 50 mph, it will take 5.88 hours.
To find average rate, you need total distance divided by total time, which is
588 miles/13.23 hours = 44.44 miles per hour.
2006-11-06 19:54:32 · answer #5 · answered by just♪wondering 7 · 0⤊ 1⤋
i'll have to say 45 mph
It doesn't matter how far because the distances are the same. You just need to find the average. 40+50 divided by 2 is 45
2006-11-06 19:40:27 · answer #6 · answered by Melody 3 · 0⤊ 3⤋
average velocity=final velocity + initial velocity/2
so 50+40=90/2=45mph
2006-11-06 19:48:55 · answer #7 · answered by Kelly 1 · 1⤊ 1⤋
It takes 7.5 Hours there and 6 Hours back...
Total 13.5 Hours
45 mph is the average speed
2006-11-06 19:43:55 · answer #8 · answered by Anonymous · 0⤊ 3⤋
well from a physics equation i know, you take the initial velocity plus the final velocity divided by two. according to that, the average speed/velocity would be 45 miles per hour.
2006-11-06 19:42:56 · answer #9 · answered by Katie 2 · 0⤊ 3⤋
45 mph?
2006-11-06 19:44:53 · answer #10 · answered by Isis 3 · 0⤊ 2⤋