average age of the participants in a mathematics competition
Source: 2007 Moldova JBMO TST p4
February 20, 2021
AverageSumcombinatorics
Problem Statement
The average age of the participants in a mathematics competition (gymnasts and high school students) increases by exactly one month if three high school age students years each are included in the competition or if three gymnasts aged years each are excluded from the competition. How many participants were initially in the contest?