EPTA Simple Math Problem? - Page 30
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Wolf
Korea (South)3290 Posts
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garbanzo
United States4046 Posts
On April 08 2011 08:24 N3rV[Green] wrote: 1/2x is simply "one half x" when said outloud. This translates to (1/2)*x, but in this case the parentheses are redundant since the equation is evaluated from left to right. This is not up for debate. Or you could read it as "1 over 2 x". | ||
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Tschis
Brazil1511 Posts
//tx | ||
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Xapti
Canada2473 Posts
On April 08 2011 08:00 Ecrilon wrote: No. Question 1 and 2 are not the same.2x has a different order than 2*x. 2x is treated as a single unit in all scientific disciplines. The answer is 2. If the equation were 48/2*(9+3) the answer would be 288. one would be 0.5x but you could just as well say x/2. What you cannot do however, is call 1/(2x) 0.5x, it must remain as 1/(2x). And while it might be common to spread things out on two lines, it won't happen all the time, such as with computer related situations, such as programming, or fast communication — It's important to set/understand the rules regarding the usage of the slash as a divider, whether it should be treated as a standard division mark, or as a grouped division, where the elements on each side are grouped as dividend and divisor. On April 08 2011 08:25 Tschis wrote: So funny how majority of people count as 288, then most are studying, and then most see it as 1/(2*x), which is basically the contrary Yeah it is a little bit interesting to me, but it's not too interesting, because I have an explanation as to why this is the case. The symbols used for division are different in each question. In the first question it uses the obelus division symbol ÷, the second it uses the slash symbol / . While to a computer it will treat the slash as an ordinary division (and very likely not recognize the obelus symbol), people might generally consider the slash to be a computerized (or compact) way of doing a vertical/grouped division, which has implied parenthesis. This would not be the case however, for people who are discussing or using computer programming though. While it is proper to add parenthesis around it when on one line to be clear, if it's on informal grounds and the rules are defined between parties, I'd say it's fine to be using it as a grouped divider without parenthesis. | ||
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Blisse
Canada3710 Posts
On April 08 2011 08:07 garbanzo wrote: 2/3*4 = (2)(1/3)(4) = (2/3)(4) != 2/(3*4) Three of those are exactly the same. The way you wrote it is completely unambiguous. The ambiguity in the original statement is in the omission of a multiplication symbol. Having back to back parentheses like that, e.g. (2)(3), counts as a multiplication symbol. Sorry, I didn't mean the products weren't the same. I meant the writing isn't the same. 3^(-1) is not the same as writing (1/3), for example. They're equivalents values, but it's like how when you write 3^(-1)4 do you mean 3^(-4) or 4[3^(-1)]. You really need the parenthesis around everything if you don't ever want to misinterpreted. Again, we're doing this online, which is only making it worse. And what happened to using { [ ( D: | ||
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Astronaut
United States52 Posts
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Zeke50100
United States2220 Posts
Which means the X is multiplied by 1/2. I think we should all make an effort to say "the quantity" whenever we mean to group multiple things as a single term >.> | ||
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gyth
657 Posts
The main thing to look out for is that you don't make any mistakes concerning the 'associativity' of any multiplication/division : a*b/c = a/c*b If I saw a/c*b I would assume a/(c*b) was meant and that any "correct" behavior was accidental not intentional. Particularly with integer math (a*b/c) != (a/c*b). My favorite occurrence of this happens in Legend of Mana. Tempering resistances should multiply by 3 then divide by 4, but since they divide by 4 then multiply by 3 the player gets better results (lower resists). | ||
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MajorityofOne
Canada2506 Posts
On April 08 2011 08:25 Tschis wrote: So funny how majority of people count as 288, then most are studying, and then most see it as 1/(2*x), which is basically the contrary //tx This is whats confusing me O.O But I think I get it now. The answer is to lose your whole f**king base. | ||
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JeeJee
Canada5652 Posts
On April 08 2011 08:27 Zeke50100 wrote: Which means the X is multiplied by 1/2. I think we should all make an effort to say "the quantity" whenever we mean to group multiple things as a single term >.> if someone tells me "1 over 2 x" they are telling me 1/(2x) not x/2, heh. if they wanted to tell me x/2, they'd say "1 over 2 times x" | ||
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garbanzo
United States4046 Posts
On April 08 2011 08:27 Zeke50100 wrote: Which means the X is multiplied by 1/2. I think we should all make an effort to say "the quantity" whenever we mean to group multiple things as a single term >.> Yes, I agree with using "the quantity" more often, but if someone (who I know knows math) were to say to me "1 over 2 x" I would think that means 1/(2x) because if he meant "one half x" then he would have said "x over 2". Edit: Dangling participle. Somewhat ironic given the discussion. | ||
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MaxField
United States2386 Posts
On April 08 2011 05:40 Disciple7 wrote: PEMDAS. First: (9+3)=12 This gives you (48) / (2) * (12) Order of operations says multiplication and division are done in the same step, therefore if you have both remaining, you go in the order that they show up. So (48) / (2) is first. 24. (24) * (12) is 288. Disappointed to see so many twos. P.S. Yes I know in PEMDAS multiplication comes first, but PEMDAS should really be PE(MD)(AS), since multiplication and division, along with addition and subtraction, are done in the same step. Edit: Had multiple frowny faces due to parentheses =( Your PEMDAS is confusing, if you follow it you have to do the Parentheses first, which is actually (MD) and (AS). haha | ||
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Zeke50100
United States2220 Posts
On April 08 2011 08:29 garbanzo wrote: Yes, I agree with that, but if someone (who I know knows math) were to say to me "1 over 2 x" I would think that means 1/(2x) because if he meant "one half x" then he would have said "x over 2". The way he wrote it, there was actually a space in between the 2 and the x, which is why I took it to be that way :D Of course, when hearing it, it's impossible to tell what they really mean, because people mix the two far to often. Which, again, is why I advocate the use of "the quantity" to signify groupings. EDIT: Of course, there are times when you would read "one half x" without changing it to just "x over two", which is what I'm getting at. | ||
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garbanzo
United States4046 Posts
On April 08 2011 08:31 Zeke50100 wrote: The way he wrote it, there was actually a space in between the 2 and the x, which is why I took it to be that way :D Of course, when hearing it, it's impossible to tell what they really mean, because people mix the two far to often. Which, again, is why I advocate the use of "the quantity" to signify groupings. The space wasn't to signify a pause, it was to signify a different "word" in the sentence.  I also agree that if someone were to say "1 over 2 [pause] x" then that would be "one half x". | ||
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VALERO
United States7 Posts
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]343[
United States10328 Posts
also lol, I'll admit I said 2. But I also said (1/2) x LOLOLOL also only 1/3 of MIT math majors I just polled said 288 :O clearly MIT math majors don't know 5th grade math :O ... but seriously, who would ever write such an expression... always use fraction bar. | ||
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garbanzo
United States4046 Posts
On April 08 2011 08:34 VALERO wrote: are people voting the wrong answers as a joke? there's no way that many people could get 5th grade math wrong If it's so unbelievable then maybe you should read the thread to see why people are getting it wrong? | ||
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space_yes
United States548 Posts
1/2 is a scalar and x is a variable. If you do the order of operations left to right you'll see the expression is actually .5x... | ||
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Sadir
Vatican City State1176 Posts
on the 1/2x stuff, I mean technically it's 0.5x (so I went for this), but if I read this in a paper, I will double check what the author means and if he means 0.5x then I tell him that his way of writing it is shitty | ||
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Alzadar
Canada5009 Posts
They would both be correct, but in different ways. | ||
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