# PUZZLE OF THE WEEK

On a sad note, this is the last Think Tank item that will appear on the Advanced Packaging Web site. The creator — “Wicks” to his many fans — is in the process of retiring, so we are phasing this feature out on the website. We thank him for his many years of service, and we thank the many loyal readers who have been regular participants. I am a firm believer in the value of extracurricular mental activity, and I’m proud that Advanced Packaging has been able to provide a little bit of that. It has been one of our most popular features.
-Jeff Demmin, Editor-in-Chief

Last Week’s Challenge: Noon Day Meal
Engineers of Makerite Plastic Co. went out for lunch on four occasions last month. The same number of engineers were present on each of the occasions. The bills were shared equally, and the chief engineer put in the same amount extra as a tip to the server. The total paid each time, including the tip, was \$174, \$148, \$252 and \$213.
How many engineers were present, and what was each person’s share on these four occasions, if the amounts were an exact number of dollars and the tip was the minimum possible?

Answer: 13 people go to lunch. The basic idea is that you have to subtract some number (the tip) from each total, and then see if the resulting four numbers are all evenly divisible by the same integer. If you start trying this with a tip of \$1, and keep working your way up, you find that the first time that each of the four numbers minus the same value is divisible by the same number is if the tip is 5 and there are 13 lunchgoers
Congratulations to Mike Wanatobe, Martin Mucciarone (Pyxis Corp.), John Desco (Agere Systems), Adam Reynolds (Technology Marketing Group), Jeno Tella, Giorgio Borre (Borre Engineering Consulting, Italy), and Brian Xia for correctly answering this puzzle.