Never mind, they got the right answer.
Tell me if this is right.
She said she used reverse multiplication. In otherwords, she started by multiplying what she knew (the speed of the moped and the speed of the bus) by number that added up to 6.
Once she found the right combination of numbers, she multiplied the speed of the moped by 60 (minutes in an hour) and got 240.
Would that work in college?
Would that work in college?
^^^^^^^^^^^^^^^^^^^^^^
No. ( Sorry)
She would have a hard time with physics, chemistry, algebra, and calculus.
That's what I would have done back in grade school, before I learned algebra (I ended up taking a bachelor's degree in mechanical engineering). And that approach certainly can yield the solution to plenty of problems - especially if implemented in a computer or programable calculator. For example, spreadsheet programs have facilities in them for doing that kind of solution search.Would that work in college?But they put that in because there are problems for which algebraic methods ] do not yield "closed form" solutions. In which case "cut and try" methods which give a "good enough" answer beat the snot out of just saying, "I don't know." I even had a boss once who praised an engineer for the way he had solved a problem by a tedious, approximate solution in a test, when the calculus solution was so simple (to the initiated) that it should have been done precisely, in two minutes flat. And that is assuming a careful check of the result.
In fact, the sort of rough hack your kid did is something that is generally prudent to do anyway, as a "sanity check" on the exact theoretical solution which - as Reply #18 illustrates, sometimes turns out to be "exactly" wrong. But I notice that the FReeper who posted #18, 22cal, reported a result which, although not accurate to the specified precision, was still in the same time zone as the correct answer. Had he, or she, arrived at a result which was outside the obvious bounds of greater than zero and less than 6, he would have checked his work more carefully and found the glitch in it.
But the bottom line is that your kid is not quite doing algebra in her attack to that problem. And in college as in real life problems, the correct result won't always - or even frequently - be a nice round number (like 4 hours, in this case). This problem is a pedagogical example, and the specific result is a matter of mere curiosity. By learning algebra one has the foundation to understand calculus, which allows one to feel competent to discuss technology at at least the layman, rather than the uncomprehending, level.So no, that should not be accepted in college.
-------------------------------------------- A while ago I went to my 50th HS reunion. I met "you" there - the place was loaded with people who I had known back in the '50s to have scant interest even in algebra, let alone calculus. But 50 years later they were fully functioning adults whom you or I instinctively accord respect to as fellow adults. And it's not like becoming an engineer assures you of making more money than someone who goes into a mundane business . . .
The unfavorable light which the school environment has a tendency to place many kids in can look pretty ridiculous in retrospect. Yes, by all means inspire your child to be what she can be - but do keep things in perspective a little, too.
“She said she used reverse multiplication. In otherwords, she started by multiplying what she knew (the speed of the moped and the speed of the bus) by number that added up to 6.
Once she found the right combination of numbers, she multiplied the speed of the moped by 60 (minutes in an hour) and got 240.”
I agree, that would be a DISASTER to approach the problem by trial and error.
Here’s a semi-viral video describing some of the junk being used in public schools.
http://www.youtube.com/watch?v=Tr1qee-bTZI