2002 AMC 12B Problem 10

Below is the professionally curated solution for Problem 10 of the 2002 AMC 12B, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2002 AMC 12B solutions, or check the answer key.

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Concepts:modular arithmeticcounting integers in a range

Difficulty rating: 1270

10.

How many different integers can be expressed as the sum of three distinct members of the set {1,4,7,10,13,16,19}?\{1,4,7,10,13,16,19\}?

1313

1616

2424

3030

3535

Solution:

Every element is one more than a multiple of 3,3, so any sum of three of them is a multiple of 3.3. The smallest sum is 1+4+7=121+4+7=12 and the largest is 13+16+19=48,13+16+19=48, and every multiple of 33 between them is attainable.

There are 1313 multiples of 33 from 1212 to 48.48.

Thus, the correct answer is A.

Problem 10 in Other Years