User Tag List
Results 1 to 15 of 18

Tue, Apr 17th, 2007, 02:00 AM #1cndladyGuest
On another board I sometimes visit how to answer a skill testing question is always a controversy. So I am going to bring the controversy here and see if it can be solved by some of you very smart people
here is one particular question
100 + 40 / 2 =
now I would do this question from left to right like this:
(100 +40)/2 =70
on this other board one of the mods has stated that
Quote:
This ongoing debate is getting tiresome.
A lot of people discuss this as if there is more than one way you can solve an equation. There is only one mathematically CORRECT way.
If the sponsor accepts the wrong answer then they are being generous because they want to award the prize and are giving you extra leeway.
In the above example the only answer ANY math teacher in the world would mark as correct is 120.
If the sponsor tried to tell you the answer was wrong you would be able to prove that they made a mistake and they would have to apologize and award you the prize. If you answered the other way and they said you were wrong there would be nothing you could do because you WOULD be wrong.
This would mean that she did the question like this
100 + (40/2) = 120
I was taught in school that if the brackets weren't there you did a string from left to right...have things changed...do you put brackets in where they weren't???
I am hoping that one of you can solve this for meThis thread is currently associated with: N/A


Tue, Apr 17th, 2007, 02:15 AM #2
 Join Date
 Mar 2006
 Location
 Kingston, Ontario
 Age
 37
 Posts
 8,840
 Likes Received
 782
 Trading Score
 6 (100%)
being a "nerd" I feel offended when you argue that 100 + 40 / 2 = is the same as (100 +40)/2 =70
This is mathematically wrong. It's like saying 1+1=3
Yes you go left to right but only for the same sign
e.g. 20 / 2 / 10 is the same as (20 / 2) / 10
note how i went from left to right in the above example
But when the signs are different things change!
Multiplication and division have higher priority to addition and subtration
e.g. 100 + 40 / 2
division has higher priority so
100 + (40 / 2)
To make things look uglier:
100 + 3 / 2 x 5 + 6 x 10 / 2
is the same as
100 + [ (3 / 2) x 5 ] + [ ( 6 x 10 ) / 2 ]
the conclusion is....
you should be thankful I don't get to write skill testing questions

Tue, Apr 17th, 2007, 02:19 AM #3cndladyGuest
well why the heck don't they put the brackets where they want them..
hmmm maybe that is why I don't win that many contests and things..
from now on I am making you do all my math questions for me

Tue, Apr 17th, 2007, 12:53 PM #4
 Join Date
 Aug 2006
 Location
 Just this side of crazy
 Posts
 1,682
 Likes Received
 5
 Trading Score
 0 (0%)
I hate math, and suck at it too.

Tue, Apr 17th, 2007, 01:27 PM #5
 Join Date
 Mar 2006
 Location
 Kingston, Ontario
 Age
 37
 Posts
 8,840
 Likes Received
 782
 Trading Score
 6 (100%)

Tue, Apr 17th, 2007, 01:29 PM #6
Oooh, oooh, I know this one. Had to rack my brain to remember. There is a convention for how to solve math equations, called Order of Operations. The way to remember is BEDMAS
B  Brackets
E  Exponents
D/M  Division and Multiplication
A/S  Addition and Subtraction
As Boo said, if there is more than one of the same group then you do them in order of left to right. Also, multiplication/division or addition/subtraction are commutative. Meaning, doesn't matter what order you do them if they are the SAME sign.
For example
2*3*5 = 30 or 5*2*3 = 30
OR 4+5+8 = 17 or 8+4+5 = 17
But NOT 4*3/6 = 2 or 6*4/3 = 8, because there are mixed signs
Unfortunately, the contest writers sometimes forget the convention, hence the confusing skilltesting questions.

Tue, Apr 17th, 2007, 01:40 PM #7
i had one that was really confusing i did really well in math at school and i know about the bracket thing but this one was really messed up i wish i could remember it

Tue, Apr 17th, 2007, 02:02 PM #8PrueGuest

Tue, Apr 17th, 2007, 07:52 PM #9
Oh, forget all that complicated stuff. Just do what I do:
Pull out your trusty calculator and punch in the question. Voila! Instant Genius.

Tue, Apr 17th, 2007, 09:06 PM #10
 Join Date
 Feb 2007
 Location
 Seattle, WA
 Posts
 956
 Likes Received
 2
 Trading Score
 0 (0%)

Tue, Apr 17th, 2007, 11:41 PM #11cndladyGuest
bcteagirl sent me this addy really explains it well
http://www.mathgoodies.com/lessons/v...perations.html

Wed, Apr 18th, 2007, 12:17 AM #12IreneWpgGuest
Whoa....have I ever been taken down a peg or three!!
I have been doing the skilltesting questions and I would have bet I had them correct. I, like Cndlady worked from left to right giving preferene to parenthesis. For example 4 + 3  6 x 7 (divide sign) 6 = my answer would have been 1.1666666......You are telling me the answer is actually 0. Right? Are you sure? I would hae bet big bucks that I was right.
[I know it's been a while since I've been in school, but I don't ever recall doing things that way.]

Wed, Apr 18th, 2007, 12:19 AM #13PrueGuest
Yup it would be 0

Wed, Apr 18th, 2007, 12:27 AM #14bcteagirlGuest
Yup... I remember having that order drilled into my head.

Wed, Apr 18th, 2007, 12:47 AM #15IreneWpgGuest
Well I have answered a lot of skilltesting questions wrong! It's no wonder I never won.
Are you sure? OK, I know you're probably right......I just can't believe I was so wrong. I don't know if I feel stupid or old.
Thread Information
Users Browsing this Thread
There are currently 1 users browsing this thread. (0 members and 1 guests)