Hi alanforde800Maximus,
We're told to cut along the solid lines, fold along the dashed lines, and tape along the solid lines to form a model of a geometric solid. This geometric solid consists of 2 pyramids, each with a square base that they share. We're asked for the sum of the number of edges and the number of faces of this geometric solid. This question has a number of built-in shortcuts that you can use to avoid doing lots of complex math.
To start, form the drawing, you can see that the shape will have 8 sides. When folded and taped together, each "edge" will be 'shared' by two of the sides. Thus, while there are 8 triangles in this shape (with 3 edges each), EVERY edge will be shared by 2 triangles, so we cannot count those edges twice. In simple terms, we have to divide the total number of edges by 2.... (8 triangles)(3 edges each)/(2... since each edge is counted twice) = 24/2 = 12 edges in the final shape.
12+8 = 20
Final Answer: C
GMAT assassins aren't born, they're made,
Rich
Last edited by
[email protected] on Wed May 16, 2018 8:15 pm, edited 1 time in total.
