math problem

I come to the experts on everything I can think of help. My teacher-wife asked me if she was calculating this correctly. I didn't
think so. What's the answer and why/how?
Chapter tests count for 60% of the final grade. Mid-term and final tests count for 40% of the final grade. Scores for chapter tests were 80, 50 and 69. Mid-term and final tests were 80 and 90. What is the final grade. One of us says 73.8 and the other says 80.7
Thanks
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On Fri, 30 Apr 2004 09:22:18 -0400, the renowned Kingfish

Okay, let's assume the chapters are *equally* weighted (with each other), as are mid-term and finals. These are assumptions. And all out of 100, natch.
1So there are 3 chapter tests, each would count for 60/3 = 20%, and two exams, which would count for 40/2 = 20% each as well. That's easy.
Just multiply each score by 0.2 and add, or to put it another way, it's less calculation to just add up all the scores and divide by 5.
I get 73.8% for the example given.
Best regards, Spehro Pefhany
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Spehro Pefhany wrote:

I think that your answer of "add it up and divide by 5" only works because the number of tests is the same ratio as the weighting. You can see this by taking an extreme case. Suppose there were 100 chapter tests and only two term tests, this would not be right.
The formula should be:
grade = ((sum(chapter tests)/number of chapter tests)*weight)+((sum(term tests)/(number of term tests)*weight)
You get the same answer but this equation works for any number of tests and any weighting.
73.78= (((80+50+69)/3)*.60)+(((80+90)/2)*.4)
I hope I didn't just do some high schoolers homework:-)
Al
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alpinekid wrote:

oops, finger check
73.8 not 73.78
Al
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On Fri, 30 Apr 2004 15:04:22 GMT, the renowned alpinekid

Yes, that is correct, as I hope I explained. Being inherently lazy and concerned with entry errors, I try to simplify things before crunching numbers (and by using an RPN calculator, of course).

This only works if the chapter tests and the exams are weighted equally with each other.
The general answer is
n --- \ G= | Wi * Si / --- i=0
Where Wi is the weight of each individual score (0 <= Wi <= 1.0) Si is each score (all must be out of 100, or at least the same number). Wi has the characteristic that
n --- \ 1.0= | Wi / --- i=0
In this case, Wi = 0.2 for i=0..5, so it can be simplified to:
5 --- \ G= 0.2* | Si / --- i=0

With the above assumption. It's also possible, for example, that the 3 chapter exams add up to 60%, but they are not equal.

Oh, well.
Best regards, Spehro Pefhany
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I must be lazier than you. I don't like to have to simplify things or worry about entry errors so I use an AE calculator, of course. <G>
Richard Coke
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Richard Coke wrote:

Being even lazier, I match your AE and raise you an APL. :-) (+/80 50 693)(+/80 902)+.x.60 .40 73.8
Ted
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I think you're bluffing. I'm sure I'm lazier than you. I call your APL and raise you a Mathcad.
Richard Coke
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On 01 May 2004 18:59:13 GMT, the renowned snipped-for-privacy@aol.com (Richard Coke) wrote:

I'm holding a MATLAB...
Best regards, Spehro Pefhany
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Spehro Pefhany wrote:

You guys and your toys! I'm talking about serious math!!
Try a recursive procedure in one of those. Well, at least you can go out for dinner while it's running.
(IBM's APL2 for OS/2) :-)
Ted
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(Richard Coke)

Darn, all I have is a copy of J.
Dan
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Dan Caster wrote:

Boy does this take me back. My first programming language was APL.
We had 3 IBM2741 in an old broom closet with a 300baud phone line to another campus that had the IBM 370-145 or maybe a 360 I forget.
WHen we got the tektronic 4013 graphic terminal and had a 1200 baud line and everyone stood in line to use it.
I wrote a graphic program what would show the soil that is retained by a retaining wall. By changing the alpha factor of the soil we could show how much the soil would slip and would influence the design of the wall.
I also remember that we learned that if we sent and 5 ibeam 3e9 command it would crash the whole ibm mainframe. Multi-user multi-tasking OS were not what they are today.
Al
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Ha ha. True story: a co-worker had his sister working in the programming division. One day she calls him up and says, 'hey, log onto VM and type in this string of characters.'
He does so, and then says, 'hey, the system just crashed!'
"I know, it's a new bug, we just found it!!"
Jim
================================================= please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ================================================
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    [ ... ]

    [ ... ]

    [ ... ]

    Some of them still are not. About ten years ago, before my wife retired, she (and the agency for which she worked) were doing testing on a rather complex database system which a contractor was trying to provide them.
    In a meeting, the contractor was boasting about how robust it was. Another co-worker said "Robust! I can bring it down with one keystroke!
    "Show us!"
    So they went to a terminal logged onto the training database, and the co-worker went through a series of steps which were all agreed to be normal things, and ended up at a (yet another*) menu. And asked "Everything is normal up to this point, right?". "Yes." "O.K., now!" and she reached out and depressed *one* key.
    It not only brought down the training database, but also the production database which was running on the same machine. :-)
* "Yet another menu" -- there were so many menus on this system, with         *No* shortcuts, that my wife and I referred to this         system as "Menu Madness". :-)
    Enjoy,         DoN.
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Ha. Her name was not "Germain" by any chance?
Jim
================================================= please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ================================================
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    Nope -- and she is no longer with us, unfortunately.
    But it sounds as though you have a story behind that name.
    Enjoy,         DoN.
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That was the one I've already related - where a sister of a co-worker called up her brother here and said 'type this in to VM' and he did so. And then "hey, the system just crashed."
"I know - it's a *bug*. We just found it!"
She was some kind of systems programmer.
Jim
================================================= please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ================================================
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DoN. Nichols wrote:

My first was hex in 1956. Yup. ALWAC 3E. Tube flip-flops, Ge diode logic, rotating drum memory, Flex-writer with paper tape reader. Key in bootstrap in binary with front panel switches, read code for high speed paper tape reader from the flex. No assembler. Code hand arranged for optimum reading (drum rotation, ya know).
First contact with APL was 1967 at U of Alberta. We were test site for APL\360.

That's the one. Special type ball for APL.

I'm surprised you had access to that. That was a privleged command.

M$ anyone?

One day I was teaching in the hardware lab (we used it for both class and lab) when there was a knock at the door. I answered it to find the Dean's secratary there with tears streaming down her face. She was holding a floppy disk and had a sad story. That afternoon was the big budget meeting and the Dean's presentation had a problem. (It was word<something>, not M$Word, things hadn't deteriorated that much yet.) They could print about half a dozen lines then it would stop. Checked the backups - same story. Was there ANYTHING I could do? I stuck the disk in the PC Junior (a good computer for its day) and looked at the directory. The reported file length seemed reasonable for the document but a TYPE command showed only a few lines. I read the file into APL and looked at the file in hex then played a hunch. +/EOF=TEXT. Answer was 2. You see, this clever word processor let you insert control codes in your document by holding down the <Ctrl> key and typing a letter. (The <Ctrl> key is right beside the shift key.) So, TEXT((TEXTEOF)/TEXT),EOF and write the file back to disk and voila. I was the local hero in the Dean's office for a while.
Ted
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Ted Edwards wrote:

I remember stumbling into that also - but I want to say I saw it years after on a DG computer. Had several 'high' level editors to look and see the whoops. Martin
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Ok - how about ICOSOHEX :-)
Martin
Martin H. Eastburn wrote:

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