Track / Stage 4 / 164 of 340 #424 of 1964

Problem 424

AMC 12 late, AIME early

Combinatorics Difficulty 4.9 Find the answer

9. In Lake Swan, there are black swans and white swans, a total of 16. Among them, the number of young swans is greater than that of adult swans. The relationship of the number of swans is:
$0<$ Adult White Swans < Young White Swans < Young Black Swans < Adult Black Swans. The number of young black swans is $\qquad$ .

Your answer

A number or a short expression. Spacing, $ signs and \frac vs / are all fine.

Official solution

$5$

Source: NuminaMath-1.5, licensed Apache-2.0. Statement and solution reproduced as published; topic, difficulty and ordering added by this site.