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Question 1199402: Kory drives from Edmonton to Lloydminster and back. Going to Lloydminster, he drives with an average speed of 96 km/h. For the return trip, he averages a speed of 100 km/h. The total time driving is 5.1 hours.
Found 3 solutions by math_tutor2020, greenestamps, josgarithmetic:
Answer by math_tutor2020(3817)   (Show Source):
You can put this solution on YOUR website!
Your post seems incomplete.
Are you wanting to know the average speed throughout the whole roundtrip?
If so, then read on.
d = the distance from Edmonton to Lloydminster
This is some positive real number
The distance is in kilometers.
x = time taken to drive from Edmonton to Lloydminster
y = time taken to drive from Lloydminster to Edmonton
The time durations are in hours.
When going to Lloydminster, we have this equation
distance = rate*time
d = 96x
Let's isolate x
x = d/96
The return journey has this equation.
distance = rate*time
d = 100y
y = d/100
The two time durations x and y must add to the total driving time of 5.1 hours.
x+y = 5.1
d/96 + d/100 = 5.1
d/96 + d/100 = 51/10
A common multiple of 96, 100, and 10 is 9600
I simply did 96*100 = 9600
We can multiply both sides of that equation by 9600 to clear out the fractions.
d/96 + d/100 = 51/10
9600*(d/96 + d/100) = 9600*(51/10)
100d + 96d = 48960
196d = 48960
d = 48960/196
d = 249.795918367347
d = 249.795918
This is the approximate distance, in kilometers, from Edmonton to Lloydminster.
The round-trip distance is twice that
2*249.795918 = 499.591836
This assumes Kory travels the same route each way.
To find the average speed throughout the round trip, we will then do the following:
distance = rate*time
rate = distance/time
rate = (499.591836 km)/(5.1 hrs)
rate = 97.959184
rate = 97.96 km per hour
Answer by greenestamps(13216)  (Show Source):
You can put this solution on YOUR website!
Since you did not ask a question, I will assume we are supposed to determine the distance between Edmonton and Lloydminster.
The distances are the same, and the ratio of the speeds is 96:100 = 24:25. That means the ratio of the times at the two speeds is 25:24.
That means 25/49 of the total time is spent at the lower speed and 24/49 at the higher speed.
25/49 of the total 5.1 hours is (25/49)(51/10)=1275/490=255/98 hours.
The distance from Edmonton to Lloydminster is (255/98)(96)=249.8km to 1 decimal place.
Answer by josgarithmetic(39631) (Show Source):
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