Do this...

Discus: SAT/ACT Tests and Test Preparation: July 2004 Archive: Do this...
 By Loop123 (Loop123) on Sunday, July 04, 2004 - 04:57 pm: Edit

Complete this problem to confirm my suspicion about some SAT preparation materials...

Simplify:

((18-3) * 2^2)/5 - 7 + (6*3 - 1)

Note that 5 is the only number in the denominator of the first term.

 By Speeddemon608 (Speeddemon608) on Sunday, July 04, 2004 - 05:00 pm: Edit

((18-3) * 2^2)/5 - 7 + (6*3 - 1)
=((15) * 4)/5 - 7 + (18 - 1)
=(60)/5 - 7 + (17)
=12 - 7 + (17)
=5 + 17
=22

 By Loop123 (Loop123) on Sunday, July 04, 2004 - 05:01 pm: Edit

Now check out the SparkNotes website that I got it from. LMAO

http://www.sparknotes.com/testprep/books/sat/chapter10section2.rhtml

 By Jefiner41 (Jefiner41) on Sunday, July 04, 2004 - 05:06 pm: Edit

Wow.. they made a mistake. lol! Instead of adding the -7 to the 17, they subtracted it like they were BOTH negative numbers. Well, forget SparkNotes..

 By Caliplaya03 (Caliplaya03) on Sunday, July 04, 2004 - 05:08 pm: Edit

Ya that's weird....and yes the answer is suppose 2 be 22 not -12....? How could they get that wrong?

 By Loop123 (Loop123) on Sunday, July 04, 2004 - 05:35 pm: Edit

It is amazing to me how the "math whizzes" at SparkNotes fail to understand one of the most fundamental areas of mathematics. I don't believe that it was a "stupid" mistake either. They stood by the flawed PEMDAS method and, as a consequence, received an incorrect answer. It disgusts me how companies as well-known as SparkNotes could release false information. How many last-minute preparation students may miss a question due to this error? Couldn't they have at least checked the answer with someone who knows what he/she is doing? After reading the majority of the material on that site, I'm sure that we CCers could make a more solid SAT preparation reference. As for me, I'm staying away from SparkNotes in fear that one of their errors could become my own.

"SparkNotes: Smarter. Better. Faster"

I don't think so.

 By Appliedmath (Appliedmath) on Tuesday, July 06, 2004 - 07:20 pm: Edit

sparknotes is useful when your class is reading a huge novel and you tuned out and you need a concise summary.

 By Chidimma (Chidimma) on Thursday, July 08, 2004 - 10:21 pm: Edit

thats funny

 By Whightknight (Whightknight) on Thursday, July 08, 2004 - 11:42 pm: Edit

the PEMDAS method is flawed ??
I just see them mistakingly having the +17 as a
-17 to get a -7 -17 which got them the -24 instead of +10

 By Loop123 (Loop123) on Friday, July 09, 2004 - 01:25 am: Edit

The PEMDAS method is, IMHO, flawed. According to this method, addition should ALWAYS come before subtraction. If this method were perfectly true, then 12-7+17 would indeed equal 12-24, because the addition would be performed before the subtraction. In reality, however, addition and subtraction occur as an expression progresses from left to right.

A more correct term would be PE(MD)(AS).

 By Conker (Conker) on Friday, July 09, 2004 - 01:32 am: Edit

When teachers teach PEMDAS to students, they explicitly state that multiplication does not necessarily come before division and the same with addition/subtraction. PEMDAS is not flawed.

 By Pcrunner17 (Pcrunner17) on Friday, July 09, 2004 - 01:34 am: Edit

Knight, they didn't just mistake the +17 as -17. It's pretty clear what they did. They looked at their rule, PEMDAS, and decided that addition should come before subtraction. Accordingly, they added the 7 and the 17 before making the final arithemetic calculation. If there is any doubt about this fact, simply follow the steps that they show you.

In my opinion, PEMDAS is not necessarily flawed -- but it can be misleading. If you don't realize that multiplication and division (or addition and subtraction, for that matter) are equal in the set order -- and must simply be taken left to right as they come, then remembering PEMDAS can lead you wrong.

 By Loop123 (Loop123) on Friday, July 09, 2004 - 01:41 am: Edit

In fact the PEMDAS method is flawed; teachers are required to explain the flaw so that students will not be pointed in the wrong direction. When the term PEMDAS is provided, it is explaining a PARTICULAR order in which procedures should be performed. When such an order is enforced, it seems that it should hold true. In fact no particular order can be stated for the order of addition/subtraction or multiplication/division without a given expression. Why, then, is one of each of these pairs explicitly stated to come first? Instead of PEMDAS, a method should be devised to group these sets of procedures instead of assigning them an inconsistent order.

 By Pcrunner17 (Pcrunner17) on Friday, July 09, 2004 - 01:44 am: Edit

Just to get my two cents in about the "PEMDAS Being Flawed" debate, I'll say this: It really all depends on what you consider to be the objective of having the PEMDAS mnemonic in the first place. If, in fact, the point of the PEMDAS system is to be able to help students remember the order of operations, then you could consider PEMDAS flawed in that it often misleads students into believing that the order displayed in the mnemonic is the order in which the operations must be followed. You note that teachers "explicity" explain the order of operations to students when using the PEMDAS system to avoid confusion. This, of course, is debatable as there are many poor teachers in the world (SPARKNOTES adding to that mix), but the point of the matter is not whether the teachers explain this to their students but, rather, what the system teaches them to retain. By its very nature, the "PEMDAS" mnemonic leads students to recite, "Parentheses, Exponents, Multiplication, Division, Addition, Subtraction." In a pinch, the student is going to remember his helpful little ditty -- the fact that the teacher made a note that two pairs of this set are equal in order may very well fail to come to mind as he recites the operations in the order of the mnemonic. With such great opportunity for leading students to make such egregious errors in the order of operations (even SPARKNOTES, a company hoping to prep students fell prey), the PEMDAS system could indeed be considered flawed if you consider its purpose to be to help students to remember the order of operations.

 By Loop123 (Loop123) on Friday, July 09, 2004 - 01:52 am: Edit

Couldn't have said it better myself, Pcrunner17.

By the way, I'd LOVE to see the diagnostic tests advertised in the banner at the bottom of their site. I can just imagine the reply to an angry student who disagrees with one of the answers: "In fact the answer is B, because according to PEMDAS..." LOL