+8261 You are running a marathon. During the first 20 miles, your average speed is 8 miles per hour. During the last 6.2 miles, you increase your average speed by 2 miles per hour. 1a: How long will it take you to run the last 6.2 miles? Use the problem solving plan with models to answer the question. 1b: A friend of yours completed the marathon in 3.2 hours. Did you finish ahead or behind your friend? Explain.
+128631 OK...I was trying to beat GL......but that seems impossible, tonight....let me explain step by step
You were running at 8 mph, but you increased it to 10 mph.
So in 60 minutes, you can run 10 miles. The question becomes, how long will it take you to run 6.2 miles?? So, setting it up as a proportion we have
t/6.2 = 60/10 where t is the time it takes to finish the 6.2 miles.....
And as we saw, that was .62hrs.....this should make sense, it should take less time to run 6.2 miles than it does to run 10 miles....
Now, to find out how long it took you to run the first 20 miles, we have
D/R = T
So
(20 miles) / (8mi/hr) = 20hr/8 = 2.5 hrs.
And 2.5 + .62 = 3.12 hrs.
Does that make sense???
+1006 I used distance/avg. speed for this problem.
[1A]
20/8 = 2.5 hours
Avg. speed increases by 2 MPH
6.2/10 = 0.62 hours = approx. 37 minutes
[1B]
2.5 + 0.62 = 3.12 hours
3.12 hours < 3.2 hours
You beat your friend. This is because you took 0.08 hours less to finish that your friend.
+8261 GoldenLeaf, what problem are you doing? Problem 1a, or problem 1b.
+128631 So, the last 6.2 miles you ran at 10mph...we can solve this usung a proportion
t/6.2 = 60/10 where t is the number of minutes you take to finish
t/6.2 = 6
t = 6(6.2) = 37.2 min = .62 hrs
So the time it took you to run the first 20 miles is given by
D/R =T 20/8 = 2.5 hrs
Add this to the time it took to run the last 6.2 miles and we have
2.5 + .62 = 3.12 hrs.
So you finished ahead of your friend.....
+1006 I did both of them.
[1A] was 37 minutes for the last 6.2 miles
[1B] was that you beat your friend.
Work in first answer.
+128631 OK...I was trying to beat GL......but that seems impossible, tonight....let me explain step by step
You were running at 8 mph, but you increased it to 10 mph.
So in 60 minutes, you can run 10 miles. The question becomes, how long will it take you to run 6.2 miles?? So, setting it up as a proportion we have
t/6.2 = 60/10 where t is the time it takes to finish the 6.2 miles.....
And as we saw, that was .62hrs.....this should make sense, it should take less time to run 6.2 miles than it does to run 10 miles....
Now, to find out how long it took you to run the first 20 miles, we have
D/R = T
So
(20 miles) / (8mi/hr) = 20hr/8 = 2.5 hrs.
And 2.5 + .62 = 3.12 hrs.
Does that make sense???
+8261 Zegroes, you are really good and funny! LOL LOL LOL LOL LOL LOL LOL LOL LOL LOL LOL
+128631 Don't get too cocky, you whippersnappers!!!.....the "fossil" still has a few tricks up his sleeve.......
