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| EV33 |
 Posted: Wed Jun 25, 2008 7:52 pm Post subject: Mistakes? |
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Forum Freshman
Joined: 04 Nov 2007
Posts: 62
Location: Washington State
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I took and test and failed it. I had to get 12/15 correct on this internet test but I think they F'd up on a few problems. I don't get any of the answers given. If you guys do tell me how you got your answer.
4. George paid $31.25 in taxi fare from the airport to the hotel. The cab charged $3.75 for the first mile plus $2.50 for each additional mile. The equation to find the number of miles, m, from the airport to the hotel would be: *
3.75 + 2.50m + 31.25 = 37.50
3.75 + 2.50m = 31.25
1.25 + 2.50m = 31.25
31.25 + 3.75 = 2.50(m-1)
3. What is the value of x in the equation? (x/3)+(2x/7)=3(2/21)
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13. A boat cruises downstream for 2 hours before heading back. It takes 3.5 hours going upstream to get back. If the speed of the stream is 8 mph, what is the speed of the boat in still water?: *
14.7 mph
19.6 mph
24.8 mph
29.3 mph |
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| Harold14370 |
| Posted: Wed Jun 25, 2008 8:58 pm Post subject: |
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Forum Professor
Joined: 13 Apr 2007
Posts: 1665
Location: Pennsylvania
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For problem 4 the answer is
1.25 + 2.50m = 31.25
The reason is, you are paying 2.50 per mile plus an extra 1.25 for the first mile and the total is 31.25. The answer is 12 miles.
For problem 3, I did not get any of the answers given. I got x=6/13
Problem 13
Distance = velocity * time
Distance downstream= ( x+8 )*2 =
Distance upstream = ( x-8 )*3.5
16+2x=3.5x-28
1.5x=44
x=29.3 |
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| William McCormick |
| Posted: Wed Jun 25, 2008 9:11 pm Post subject: Re: Mistakes? |
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Forum Professor
Joined: 03 Apr 2008
Posts: 1283
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| EV33 wrote: |
I took and test and failed it. I had to get 12/15 correct on this internet test but I think they F'd up on a few problems. I don't get any of the answers given. If you guys do tell me how you got your answer.
4. George paid $31.25 in taxi fare from the airport to the hotel. The cab charged $3.75 for the first mile plus $2.50 for each additional mile. The equation to find the number of miles, m, from the airport to the hotel would be: *
3.75 + 2.50m + 31.25 = 37.50
3.75 + 2.50m = 31.25
1.25 + 2.50m = 31.25
31.25 + 3.75 = 2.50(m-1)
3. What is the value of x in the equation? (x/3)+(2x/7)=3(2/21)
3
5
7
9
13. A boat cruises downstream for 2 hours before heading back. It takes 3.5 hours going upstream to get back. If the speed of the stream is 8 mph, what is the speed of the boat in still water?: *
14.7 mph
19.6 mph
24.8 mph
29.3 mph |
You cannot actually answer that last question without an assumption.
You do not know if the boat was powered with the same power downstream as up.
So you do not know the distance traveled without an assumption. You may have left something out though.
However if you did not, this is a question that is not about teaching, but rather to start poor habits.
Tests are for fifth world nations. American's don't try to do anything they just do it.
The time you waste making up tests you could use to solve real problems. Of course it will instantly bring you under fire for being a bold powerful American citizen, that obviously sees the shortcomings in law makers.
Sincerely,
William McCormick
_________________
Warning: Any information contained in this post could be part of a conspiracy to make you stupid. So only use it if you understand it. Use at your own risk.
http://www.Rockwelder.com |
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| JaneBennet |
| Posted: Wed Jun 25, 2008 10:09 pm Post subject: Re: Mistakes? |
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Forum Ph.D.
Joined: 06 Apr 2008
Posts: 874
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| William McCormick wrote: |
| EV33 wrote: |
13. A boat cruises downstream for 2 hours before heading back. It takes 3.5 hours going upstream to get back. If the speed of the stream is 8 mph, what is the speed of the boat in still water?: *
14.7 mph
19.6 mph
24.8 mph
29.3 mph |
You cannot actually answer that last question without an assumption.
You do not know if the boat was powered with the same power downstream as up.
So you do not know the distance traveled without an assumption. You may have left something out though.
However if you did not, this is a question that is not about teaching, but rather to start poor habits.
Tests are for fifth world nations. American's don't try to do anything they just do it.
The time you waste making up tests you could use to solve real problems. Of course it will instantly bring you under fire for being a bold powerful American citizen, that obviously sees the shortcomings in law makers. |
I think I’m going to cut & paste this on all the Internet forums I visit so as to give everybody a good laugh. In fact, I think I’m going to join some new forums just to cut & paste this there and share the joke around.
In fact, I think I should print this out, frame it and take it with me wherever I go. Then whenever I’m feeling down, I only have to take it out and read it, and my depression will be instantly cured.
_________________
Did You Know?
Random Fact: Pablo Neruda |
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| serpicojr |
| Posted: Wed Jun 25, 2008 10:28 pm Post subject: |
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Forum Professor
Joined: 17 Jul 2007
Posts: 1128
Location: JRZ
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| William, don't call sour grapes just because you don't understand high school algebra. |
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| EV33 |
| Posted: Wed Jun 25, 2008 11:01 pm Post subject: |
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Forum Freshman
Joined: 04 Nov 2007
Posts: 62
Location: Washington State
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| Darn it. Yea I got the same thing for 3 but I didn't think you could do the other ones, I figured there was something I was missing though. |
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| William McCormick |
| Posted: Thu Jun 26, 2008 10:08 pm Post subject: Re: Mistakes? |
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Forum Professor
Joined: 03 Apr 2008
Posts: 1283
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| JaneBennet wrote: |
| William McCormick wrote: |
| EV33 wrote: |
13. A boat cruises downstream for 2 hours before heading back. It takes 3.5 hours going upstream to get back. If the speed of the stream is 8 mph, what is the speed of the boat in still water?: *
14.7 mph
19.6 mph
24.8 mph
29.3 mph |
You cannot actually answer that last question without an assumption.
You do not know if the boat was powered with the same power downstream as up.
So you do not know the distance traveled without an assumption. You may have left something out though.
However if you did not, this is a question that is not about teaching, but rather to start poor habits.
Tests are for fifth world nations. American's don't try to do anything they just do it.
The time you waste making up tests you could use to solve real problems. Of course it will instantly bring you under fire for being a bold powerful American citizen, that obviously sees the shortcomings in law makers. |
I think I’m going to cut & paste this on all the Internet forums I visit so as to give everybody a good laugh. In fact, I think I’m going to join some new forums just to cut & paste this there and share the joke around.
In fact, I think I should print this out, frame it and take it with me wherever I go. Then whenever I’m feeling down, I only have to take it out and read it, and my depression will be instantly cured. |
The boat is going to have to raise itself perhaps a mile or more. That is horse power. When you are talking about a boat that might weigh 500,000 pounds.
Going up stream. You would need to know if the boat is going the same speed downstream as upstream in order to calculate the difference the height created.
But you are welcome to post my answer.
Sincerely,
William McCormick
_________________
Warning: Any information contained in this post could be part of a conspiracy to make you stupid. So only use it if you understand it. Use at your own risk.
http://www.Rockwelder.com |
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| William McCormick |
| Posted: Thu Jun 26, 2008 10:34 pm Post subject: |
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Joined: 03 Apr 2008
Posts: 1283
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Also a boat has a sweet spot, its maximum efficiency. In both engine RPM and hull design. So that when you push a boat past a certain speed, its hull is no longer capable of the same efficiency. Unless you can get it into a plane or prop ride.
The engines, shaft and propeller have an optimum range. You would need to know what the effect of fighting an eight mile an hour current will do to the engine performance.
So you would need to know the answer to that question in order to answer it.
I had an International Unlimited ships captain license long before I was eighteen years old, I think I was twelve when I could captain any ship on earth. I just got it so I could captain a vessel in local waters under age. The training and test, was issued by the United States Navy Waves.
Sincerely,
William McCormick
_________________
Warning: Any information contained in this post could be part of a conspiracy to make you stupid. So only use it if you understand it. Use at your own risk.
http://www.Rockwelder.com |
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| serpicojr |
| Posted: Thu Jun 26, 2008 10:53 pm Post subject: |
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Forum Professor
Joined: 17 Jul 2007
Posts: 1128
Location: JRZ
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| William, replace every instance of "boat" with "Billy McC" and every instance of "stream" with "moving sidewalk" and then shut up. The point is: this isn't a question about boats, this is a question about algebra. If you say boat one more time, I'll have to... be rude to you again. |
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| JaneBennet |
| Posted: Fri Jun 27, 2008 6:30 am Post subject: |
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Forum Ph.D.
Joined: 06 Apr 2008
Posts: 874
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William McCormick, in case you missed it:
| Harold14370 wrote: |
Problem 13
Distance = velocity * time
Distance downstream= ( x+8 )*2 =
Distance upstream = ( x-8 )*3.5
16+2x=3.5x-28
1.5x=44
x=29.3 |
If you don’t understand the maths, then just shut up, okay? It’s not your question, and none of your business. 
You have caused enough mischief in the Physics forum. Please keep out of the Mathematics forum.
_________________
Did You Know?
Random Fact: Pablo Neruda |
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| William McCormick |
| Posted: Fri Jun 27, 2008 6:39 pm Post subject: |
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Forum Professor
Joined: 03 Apr 2008
Posts: 1283
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| JaneBennet wrote: |
William McCormick, in case you missed it:
| Harold14370 wrote: |
Problem 13
Distance = velocity * time
Distance downstream= ( x+8 )*2 =
Distance upstream = ( x-8 )*3.5
16+2x=3.5x-28
1.5x=44
x=29.3 |
If you don’t understand the maths, then just shut up, okay? It’s not your question, and none of your business.
You have caused enough mischief in the Physics forum. Please keep out of the Mathematics forum. |
That will not tell you anything about a boat traveling on a river, at an unknown speed. With a river elevating at an unknown angle.
Sorry, that is the real world of math.
If the free speed of the boat is set to eight miles per hour, it will slip downstream, in the river heading up stream against an 8 mile an hour flow. Because a moving river is on an angle.
You would need to know the elevation of the river, and the effects of hull and drive train at elevated RPM. That is math A+ style.
Anyone that answered the question right, would probably die on the river, or run out of gas. That is not the purpose of math.
Yelling in big letters is not the purpose of a math forum.
Math is a fun calm thing for all.
Sincerely,
William McCormick
_________________
Warning: Any information contained in this post could be part of a conspiracy to make you stupid. So only use it if you understand it. Use at your own risk.
http://www.Rockwelder.com |
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| Ophiolite |
| Posted: Fri Jun 27, 2008 8:36 pm Post subject: |
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Forum Radioactive Isotope
Joined: 25 Jul 2005
Posts: 4804
Location: Scotland
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William,
you can face a ban, or you can behave yourself. Your choice. I'm running out of patience.
So we don't misunderstand each other, this is an official warning.
Ophiolite
_________________
The Universe is not only weirder than we imagine it is weirder than we can imagine. J.B.S.Haldane. |
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| William McCormick |
| Posted: Fri Jun 27, 2008 11:26 pm Post subject: |
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Forum Professor
Joined: 03 Apr 2008
Posts: 1283
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Here is something I feel strongly about.
If you were to offer that problem to students, as
A hobby radio controlled race car on a toy manufacturing conveyor belt, starts up and runs down the very long conveyor for 2 hours.
Then suddenly turns around and heads up the conveyor for 3.5 hours.
The car maintains a constant wheel speed.
The conveyor belt is moving at 8 miles per hour. What was the speed of the car?
Those that are interested could answer it. And if the teacher called on me I could say "What Harold said"
I look at it like the river traveled 8 miles an hour for 5.5 hours or 44 miles. Causing a 1.5 hour difference between the two directions.
Making a ratio of 1.5/5.5 = 44/Total miles. So if you multiply 5.5 by 44 you get 242 and when you divide that by 1.5 you get 161.33333333333333333333333333333 the total miles traveled. By dividing the two fractions you create a 1 divided by 1 scenario and you just fill in the blank by dividing by 1.5
Then you can get the miles per hour by dividing by 5.5, and check it by dividing 161.3333333 by 1.5 and getting 44.
But that original question is just to far away from reality for an intelligent individual that actually knows how things work. It is a very poor question. Asking you to make assumptions. Rewarding someone for their assumption.
That is not math. I could not even imagine what the question was trying solve. This I am totally serious about.
To truly understand the math though, you have to realize that the difference created in the respective times of travel in each direction, is a concatenation of the miles the river traveled.
But in real life this equation would not work for a boat.
I think teachers use tests to hide that they already know that class sucks and not many are learning, by catching the kids flipping them the bird kind of out of the corner of their eye. And the derogatory graffiti on school equipment. Students do not need tests. They need teachers.
Sincerely,
William McCormick
_________________
Warning: Any information contained in this post could be part of a conspiracy to make you stupid. So only use it if you understand it. Use at your own risk.
http://www.Rockwelder.com |
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| William McCormick |
| Posted: Fri Jun 27, 2008 11:28 pm Post subject: |
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Joined: 03 Apr 2008
Posts: 1283
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| Ophiolite wrote: |
William,
you can face a ban, or you can behave yourself. Your choice. I'm running out of patience.
So we don't misunderstand each other, this is an official warning.
Ophiolite |
I just caught your post. Is there something that you can highlight for me about what is not correct for a math forum?
I am meaning no insult or injury. I would hope math does not hurt anyone.
Sincerely,
William McCormick
_________________
Warning: Any information contained in this post could be part of a conspiracy to make you stupid. So only use it if you understand it. Use at your own risk.
http://www.Rockwelder.com |
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| serpicojr |
| Posted: Sat Jun 28, 2008 9:24 am Post subject: |
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Joined: 17 Jul 2007
Posts: 1128
Location: JRZ
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William: I'll agree with you that, if we wanted to get the real answer to the question, we'd need more information and a more careful analysis. However, let's look at the context of the problem.
First, this is clearly from an introductory algebra class, so we can assume that the EV33 and his classmates do not have a lot of advanced science under their belt and are thus unlikely to reach the objections that you raise. Asking for a more detailed answer than the one Harold gave is inappropriate.
Second, problems like this were likely covered in EV33's class, whether in lecture, in the text, or in homework, and the general method of solving these questions in the context of the course was probably covered. So the students probably knew what sort of solution was expected of them in this problem, even if they realized that the problem was more complicated than said solution suggests.
Third, the point of this problem is not to test the students' understanding of nautical travel. The point of the problem is to test the students' understanding of algebra and its applications, in particular applying simple linear equations in one variable. Asking for anything more detailed than this is asking the student to go beyond the math that they have developed so far.
So your complaints really aren't relevant to the discussion at hand, as you're ignoring the context of the problem. Feel free to open up a new thread about the nature of boats moving through moving water, but understand that you have once again ruined a discussion due to your missing the point. |
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