find next number in sequence 6, 3, 9, 9/2, 81/4, ....

E

EWallace2012

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Apr 17, 2007
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okay so, it says what is the next number in the seqence?

**(important the /'s are frations)**

6, 3, 9, 9/2, 81/4

6-3=3
9-3=6
9/2-9= 4 1/2
81/4-9/2= 15 3/4

uhh?? :?: :?
 
First, this isn't a math problem. It is a parlor game played in many math classes.
Second, you need 3-6, not 6-3.
Third, 9/2 - 9 is negative.
Fourth, that isn't getting you anywhere, is it?
Fifth, sequential ratios won't help, either.
Sixth, since this is just a parlor game, try thinking of something silly, like dividing in half on one step and squaring in the next, then repeating the two steps.

6/2 = 3

3^2 = 9

9/2 = 9/2

(9/2)^2 = 81/4

(81/4)/2 = ??

Seventh, ANY number you can justify should be treated as a correct response. I'm kind of fond of 549/4. I can argue it and motivate it. If someone dared to mark it wrong, they WOULD hear from me.

Eighth, the REAL answer is -2. :wink:
 
EWallace2012 said:
6, 3, 9, 9/2, 81/4
Click to expand...
As the first tutor suggested, any answer that you can justify (logically, mathematically, etc) should be acceptable (as long as you provide a clear statement of your reasoning). But "the" right answer is whatever the author had in mind when he composed the exercise.

My guess is that the pattern is an every-other-step sort of thing: divide by 2, square, divide by 2, square, divide by 2, square, .... But your guess, as long as it's sensible, is as good as anybody else's.

Eliz.

P.S. Welcome to FreeMathHelp! :D
 
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