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It took Ellen 6 hours to ride her bike a total distance of 120 miles. 29 May 2011, 22:50
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25% (medium)

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81% (02:21) correct 19% (01:48) wrong based on 308 sessions

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It took Ellen 6 hours to ride her bike a total distance of 120 miles. For the first part of the trip, her speed was constantly 25 miles per hour. For the second part of her trip, her speed was constantly 15 miles per hour. For how many miles did Ellen travel at 25 miles per hour?

A. 60
B. 62.5
C. 66 2/3
D. 75
E. 90­
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D
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It took Ellen 6 hours to ride her bike a total distance of 120 miles. 29 May 2011, 23:18
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time for 1st part + time for 2nd part = total time
time for 1st part = d/25
time for 2nd part = (120-d)/15

so, d/25 + (120-d)/15 = 6
Solving for d, d = 75 miles. Choice D.
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It took Ellen 6 hours to ride her bike a total distance of 120 miles. 29 May 2011, 23:20
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t1= d1/25 t1 and d1 is the time and distance traveled at 25miles/hr
t2=d2/15 t2 and d2 is the time and distance traveled at 15miles/hr

t1+t2=6
d1/25 +d2/15 = 6 --(1)

also, d1+d2=120 ---(2)

solving (1) and (2) for d1
d1=75.
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It took Ellen 6 hours to ride her bike a total distance of 120 miles. 21 Jan 2019, 19:50
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shrive555
It took Ellen 6 hours to ride her bike a total distance of 120 miles. For the first part of the trip, her speed was constantly 25 miles per hour. For the second part of her trip, her speed was constantly 15 miles per hour. For how many miles did Ellen travel at 25 miles per hour?

60
62.5
66 2/3
75
90
Show more

Let x = the number of hours Ellen rode her bike at 25 mph. Thus we have the following equation for the distance she rode:

25x + 15(6 - x) = 120

25x + 90 - 15x = 120

10x = 30

x = 3

So Ellen traveled at 25 miles per hour for 3 hours, for a total distance of 25 x 3 = 75 miles.

Answer: D
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It took Ellen 6 hours to ride her bike a total distance of 120 miles. 29 Aug 2024, 03:41
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Hi
I did this using the differntial method of averages

Total avg speed = 120 miles/6 hrs = 20 miles/hr

Now using differential method we find ratio of Times = Time for first : Time for second leg = 20-15:25-20 so ratio of time is 5:5 or 1:1

So time for first leg of journey is 3 hrs

Distance is 3*25 = 75 MILES

@Bunnel is my approach correct
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It took Ellen 6 hours to ride her bike a total distance of 120 miles. 29 Aug 2024, 03:55
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Kavicogsci
It took Ellen 6 hours to ride her bike a total distance of 120 miles. For the first part of the trip, her speed was constantly 25 miles per hour. For the second part of her trip, her speed was constantly 15 miles per hour. For how many miles did Ellen travel at 25 miles per hour?

A. 60
B. 62.5
C. 66 2/3
D. 75
E. 90­

Hi
I did this using the differntial method of averages

Total avg speed = 120 miles/6 hrs = 20 miles/hr

Now using differential method we find ratio of Times = Time for first : Time for second leg = 20-15:25-20 so ratio of time is 5:5 or 1:1

So time for first leg of journey is 3 hrs

Distance is 3*25 = 75 MILES

@Bunnel is my approach correct
Show more

That's correct. Since the average speed (20 miles per hour) is the average of the individual speeds (25 and 15 miles per hour), this implies that Ellen spent half of the total time of 6 hours riding at 25 miles per hour and the other half at 15 miles per hour.
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It took Ellen 6 hours to ride her bike a total distance of 120 miles. 16 Sep 2025, 05:03
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