2008 AMC 10B Problems/Problem 13
Problem
For each positive integer , the mean of the first terms of a sequence is . What is the term of the sequence?
Solution
Since the mean of the first terms is , the sum of the first terms is . Thus, the sum of the first terms is and the sum of the first terms is . Hence, the 2008th term is
Note that is the sum of the first n odd numbers.
Solution 2 (Using Answer Choices)
From inspection, we see that the sum of the sequence is basically . We also notice that Is the sum of the first ODD integers. Because is the only odd integer, is the answer.
See also
2008 AMC 10B (Problems • Answer Key • Resources) | ||
Preceded by Problem 12 |
Followed by Problem 14 | |
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