Answer:
E 840 cm
Step-by-step explanation:
For a 20×20 grid, there will be 21 strands in the vertical direction, and 21 in the horizontal direction. Each strand wil be 20 cm long. The total length is ...
(20 cm)(2 × 21) = 840 cm
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Additional comment
In this case, we take "similar" to mean that the grid squares are 1 cm, and the wire encloses a larger array of those squares.
In geometry, the term "similar" would mean the larger grid is simply a scaled-up version of the smaller one, with squares that are 20/3 cm, instead of 1 cm. The length of wire required in that case is (4+4)(20 cm) = 160 cm = (20/3)×(24 cm).
