2003 AMC 10B Problem 3

Below is the professionally curated solution for Problem 3 of the 2003 AMC 10B, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2003 AMC 10B solutions, or check the answer key.

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Concepts:summationlinear equation

Difficulty rating: 880

3.

The sum of 55 consecutive even integers is 44 less than the sum of the first 88 consecutive odd counting numbers. What is the smallest of the even integers?

66

88

1010

1212

1414

Solution:

The first 88 odd counting numbers sum to 1+3++15=64.1+3+\cdots+15=64.

Letting nn be the smallest even integer, n+(n+2)+(n+4)+(n+6)+(n+8)=5n+20=60,n+(n+2)+(n+4)+(n+6)+(n+8)=5n+20=60, so n=8.n=8.

Thus, the correct answer is B.

Problem 3 in Other Years