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Proving a witch weighs the same as a duck (Posted on 2005-02-21) Difficulty: 2 of 5
Suppose the witch weighs W pounds, and the duck weighs D pounds. Also, suppose their average weight is A pounds. (Their combined weight is 2A)

W + D = 2A. (Given)
W = 2A - D. (Subtract D)
W - 2A = -D (Subtract 2A)
W(W - 2A) = W(-D) (Multiply by W)
W(W - 2A) = (2A - D)(-D) (Substitute 2A-D for W using the given equation)
W - 2AW = -2AD + D (Distribute)
W - 2AW + A = D - 2AD + A (Add A)
(W-A)(W-A)=(D-A)(D-A). (Factor)
(W-A) = (D-A)². (An expression times itself equals the expression squared)
(W-A) = (D-A) (Square root)
W = D (Add A)

In other words, a witch weighs the same as a duck.

Where did I go wrong?

See The Solution Submitted by Dustin    
Rating: 3.0000 (4 votes)

Comments: ( You must be logged in to post comments.)
  Subject Author Date
re(3): Monty Python logical methodBruce Brantley2005-02-24 14:53:24
SolutionPossible solutionRobyn2005-02-24 01:10:08
re(2): Monty Python logical methodLarry2005-02-23 11:37:05
SolutionIt's elementary (elementary math)Penny2005-02-22 21:17:31
re: Monty Python logical methodBruce Brantley2005-02-22 18:02:45
PERHAPSRex2005-02-22 14:40:02
Monty Python logical methodLarry2005-02-22 02:40:16
some thoughtsmomo2005-02-21 16:30:53
Solutionnp_rt2005-02-21 16:25:08
solutionjoseph2005-02-21 15:19:59
SolutionSpoilerSteve Herman2005-02-21 15:08:00
SolutionWho says they don't weight the same? (solution)Jer2005-02-21 15:05:24
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