1998 CEMC Gauss (Grade 7) Problems/Problem 7

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Problem

A rectangular field is 80 m long and 60 m wide. If fence posts are placed at the corners and are 10 m apart along the 4 sides of the field, how many posts are needed to completely fence the field?

$\text{(A)}\ 24 \qquad \text{(B)}\ 26 \qquad \text{(C)}\ 28 \qquad \text{(D)}\ 30 \qquad \text{(E)}\ 32$

Solution

There is one post on each of the corners.

There are 7 posts along each of the two lengths and 5 posts along each of the two widths.

In total, this gives us $\boxed{\textbf{(C)}\ 28}$ posts.

-edited by coolmath34

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