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Two Fields (Posted on 2004-08-06) Difficulty: 2 of 5
A farmer has two rectangular fields with a peculiar relationship. Both fields have integer dimensions. The corn field has three times the area of the hay field but the hay field has three times the perimeter.

It is also known that the dimensions of the corn field differ by 1, and the shorter dimension of the hay field is less than 100.

Find the dimensions of the two fields.

  Submitted by Brian Smith    
Rating: 2.2500 (4 votes)
Solution: (Hide)
Call the shorter edge of the corn field C, the shorter edge of the hay field B and the longer egde A.

The problem states c*(c+1) = 3*ab [area] and 3*2*(c+c+1) = 2*(a+b).

The second equation can be written as c = (a+b-3)/6.
Substituting into the first equation yields ((a+b-3)/6)*((a+b+3)/6) = 3*a*b

This equation can be solved for a as follows: (a+b)^2 - 9 = 108*a*b
a^2 + 2*a*b + b^2 - 108*a*b = 9
(a - 53*b)^2 = 9 + 2808*b^2
a = 53*b +/- sqrt(9 + 2808*b^2)

Testing values of b less than 100, as specified in the problem, gives only one value of b: b=3.
If b=3 then a = 109 +/- 159, a = -50 or 318. Since a must be positive, a = 318. c then equals 53

The corn field is 53x54 and the hay field is 3x318.

Comments: ( You must be logged in to post comments.)
  Subject Author Date
Some ThoughtsNo SubjectJayDeeKay2007-06-19 10:34:15
AnswerK Sengupta2007-03-09 05:05:03
SolutionSolutionHot Date Dave2004-08-06 11:29:53
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