1990 AMC 8 Problem 18
Attempt Problem 18 of the 1990 AMC 8 below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 1990 AMC 8 solutions, or check the answer key.
All problems are used with official legal permission of the Mathematical Association of America (MAA).
18.
Every corner of a rectangular prism is cut off by a straight slice through the three edges meeting at that corner, removing a small triangular piece at each of the eight corners. How many edges does the new figure have?
Answer: C
Small hint:
The original rectangular prism has edges, and none of them disappear
Big hint:
Each corner cut creates a new triangular face, adding new edges
Solution:
A rectangular prism starts with edges, and cutting corners only shortens them without removing any.
Each of the corner cuts creates a small triangular face with new edges, adding edges. The total is .
Thus, the correct answer is C .
Problem 18 in other years
- 1985 AMC 8
- 1986 AMC 8
- 1987 AMC 8
- 1988 AMC 8
- 1989 AMC 8
- 1991 AMC 8
- 1992 AMC 8
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