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muser
science forum addict
Joined: 02 May 2005
Posts: 67
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 Posted: Sun Apr 02, 2006 3:42 pm Post subject:
dividing
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I probably should have paid more attention at school, but 9900 / 90% =
11000.
Can anyone explain what the end result of this question is, in relation
to the sum. i.e. I have 9900 units but this 90% of a total I need. Is
11,000 units that total? If I divid by 80% the total rises, I just
can't get my mind around it. Thank you in advance. |
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mensanator@aol.compost
science forum Guru
Joined: 24 Mar 2005
Posts: 826
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| Posted: Sun Apr 02, 2006 4:25 pm Post subject:
Re: dividing
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muser wrote:
| Quote: | I probably should have paid more attention at school, but 9900 / 90% =
11000.
Can anyone explain what the end result of this question is, in relation
to the sum. i.e. I have 9900 units but this 90% of a total I need. Is
11,000 units that total? If I divid by 80% the total rises, I just
can't get my mind around it. Thank you in advance.
|
The word "of" means multiply.
3/4 of 100 is (3/4)*100 = 300/4 = 75.
A percentage is just another fraction which, by definition,
always has 100 in the denominator.
So 90% of 9900 is (90/100)*9900 = 891000/100 = 8910
Ah, but you didn't ask for that. You asked what 9900
DIVIDED by 90% was. So invert the fraction and multiply.
(100/90)*9900 = 990000/90 = 11000
If that's not what you meant, then the answer was 8910.
And 80% OF 9900 is (80/100)*9900 = 7920. |
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muser
science forum addict
Joined: 02 May 2005
Posts: 67
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| Posted: Sun Apr 02, 2006 4:32 pm Post subject:
Re: dividing
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sorry I didn't explain my query properly. 9900 / 90% = 11000. My
question is this, what does the 11,000 represent? It isn't 90% of 9900,
as that is 8910. I hope that helps. I'm not a troll, just someone who
never understood maths. |
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Jasen Betts
science forum Guru Wannabe
Joined: 31 Jul 2005
Posts: 176
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| Posted: Mon Apr 03, 2006 10:23 am Post subject:
Re: dividing
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On 2006-04-02, muser <charlie12345@hotmail.com> wrote:
| Quote: | I probably should have paid more attention at school, but 9900 / 90% =
11000.
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90% is another way to write
90
-----
100
Bye.
Jasen |
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Jasen Betts
science forum Guru Wannabe
Joined: 31 Jul 2005
Posts: 176
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| Posted: Mon Apr 03, 2006 10:25 am Post subject:
Re: dividing
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On 2006-04-02, muser <charlie12345@hotmail.com> wrote:
| Quote: | sorry I didn't explain my query properly. 9900 / 90% = 11000. My
question is this, what does the 11,000 represent? It isn't 90% of 9900,
as that is 8910. I hope that helps. I'm not a troll, just someone who
never understood maths.
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9900 is 90% of 11000
Bye.
Jasen |
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Dave
science forum beginner
Joined: 03 Feb 2006
Posts: 27
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| Posted: Mon Apr 03, 2006 10:46 am Post subject:
Re: dividing
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muser wrote:
| Quote: | Fred I use to post on alt.c++, on there you will meet the most
obnoxious people imaginable.
You say don't call it a total "Don't call it a total", then you say
multiply y by x/100.
Then "> the total rises". Isn't the total meant to be when you add
things, not multiply.
I'm being pedantic, but only to show you why I think you are being
unhelpful in your post,
hence me asking you not to respond in the first place.
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Fred's post is actually quite clear. It's a shame you felt offended
when he said you shouldn't use "total" to describe a number that isn't a
sum of other numbers, then allowed that offence to stop you
understanding his post.
The problem with asking him not to respond is that you are effectively
asking anyone else who is likely to post a clear answer not to respond.
If you think Fred's a complete idiot, ignore him; you said in another
post you've been around Usenet for a while so you should know by now
that trolls are best left unfed. If he says stuff that is misleading,
you can trust the rest of us to correct him. But if we don't correct
him, then he is right, and if you don't understand him then that is not
because Fred is wrong or an idiot and your best response in this case is
to ask for clarification. Accusing Fred of being an idiot when you
don't understand his responses, or don't like his style, or whatever,
puts you at risk of identifying yourself as an idiot.
So I'm expecting to get flamed by you as a result of this helpful post.
If that happens, you can kiss bye-bye to any help from me in the
future and also to help from others on the NG who don't want to be
flamed for being (in their opinion) helpful.
I don't understand this:
| Quote: | Then "> the total rises". Isn't the total meant to be when you add
things, not multiply.
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"the total rises" is a quote of your post, not something Fred wrote.
Your complete sentence was "If I divid by 80% the total rises, I just
can't get my mind around it."
Two ways of getting your head round it:
If you think of a percentage as a fraction, that can help. 80% =
80/100. Dividing fractions is difficult, but a workaround is to flip
the second fraction and multiply instead, so (a/b) / (c/d) = (a/b) *
(d/c). So dividing by 80% is equivalent to multiplying by 100/80.
So for a simple example, 10 / (1/2) = 10 * (2/1) = 20.
Alternatively you could consider division by numbers less than, equal to
and greater than 1. If you divide by 1, nothing happens. If you divide
by something greater than one, the result is smaller than the something
(10/2=5 for example). So if you divide by something smaller than 1,
it's logical that the result would be larger than that something (so
10/.5>10, and 9900/0.9>9900 and you can calculate the exact answer as
Fred showed you).
The only change I'd make to Fred's post is to change "= 90 * x/100" to
"= x * 90/100" so you can see that 90/100 comes from 90%. But that's
only because I know spreading stuff around can muddy the thought process
and leave you asking "where did THAT come from?"; it's mathematically
equal and only really a style point rather than an accuracy point.
Dave. |
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Frederick Williams
science forum addict
Joined: 19 Nov 2005
Posts: 97
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| Posted: Mon Apr 03, 2006 2:02 pm Post subject:
Re: dividing
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muser wrote:
| Quote: |
Fred I use to post on alt.c++, on there you will meet the most
obnoxious people imaginable.
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C++ is enough to addle anybody's brain. Maybe their therapists will
wean them off C++ and on to Java, or even Python. Fetch the comfy
chair!
--
Remove "antispam" and ".invalid" for e-mail address. |
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