SOLUTION: A chair is being re-upholstered. The back is a square, 27" x 27". 7/16" diameter(head)tacks are placed uniformly,1/4" apart, around the square. Determine number of tacks used.

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Question 1166407: A chair is being re-upholstered. The back is a square, 27" x 27". 7/16" diameter(head)tacks are placed uniformly,1/4" apart, around the square. Determine number of tacks used.
Answer by Edwin McCravy(20065) About Me  (Show Source):
You can put this solution on YOUR website!
The perimeter, 4*27" = 108" consists of n tacks and n-1 gaps between them, so

n%287%2F16%29%2B%28n-1%29%281%2F4%29=108

Solve that for n, get

1732%2F11=157%265%2F11

so there's 157 tacks and the extra 5/11" of space is because the tacks are not
exactly tangent to the edge.

Edwin