But if you gloss “needs” as minimum required without fixing the shape, none of the answers are correct, since she could make a circular blanket and would only need 2*pi*sqrt(12/pi) (approx 12.28) units of border, or if you specify rectangular, but not the dimensions she could get by with a 4*sqrt(12) which is a little less than 14 units.
Yes, we’re completely tossing out shape.
And shape is not unreasonable to consider at all from a practical standpoint. There are ovals to consider, etc. I once received a triangular-shaped pillow as a gift.
Is math not about precision ???
Questions must be formed precisely.
This question simply smells like a lazy teacher or one who has very little clue about math/logic.