Sunday Times Teaser 2822 – Losing Weight
by Michael Fletcher
Published: 23 October 2016 (link)
The members of our local sports club are split into two groups. Originally the groups had the same number of members, and the first group contained member Waites who weighed 100kg (and indeed that was the average weight of the members of the first group). Then the club trainer decided that the groups were overweight and that, for each of the next ten weeks, for each group the average weight of the members should be reduced by one kilogram.
This was achieved by simply transferring a member from the first group to the second group each week, and Waites was the tenth member to be transferred.
How many members are there in the club?