tree's problem with average Austria Beginners' Competition 2010 p2
Source:
October 3, 2021
algebra
Problem Statement
In a national park there is a group of sequoia trees, all of which have a positive integer age. Their average age is years. After a year old building was destroyed by lightning, the average age drops to years. How many trees were originally in the group? At most, how many of them were exactly years old?(W. Janous, WRG Ursulinen, Innsbruck)