Problem:
A "stair-step" figure s made up of alternating black and white squares in each row. Rows through are shown. All rows begin and end with a white square. The number of black squares in the th row is
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Answer Choices:
A.
B.
C.
D.
E.
Solution:
The number of black squares is one less than the number of the row, so the th row contains black squares.
Answer: .
The problems on this page are the property of the MAA's American Mathematics Competitions