Mike Strub Challenge

Dr. Strub was walking down a road contemplating whatever it is that a man of Dr. Strub's infinite powers would contemplate, which is another way of saying "Who knows?", when he happened upon a newly established Weyerhaeuser plantation. 

Due to Weyerhaeuser's superior genteics and advanced silvicultural prescriptions, Weyerhaeuser plantations are all established on an exact 1'x1' (1' = 1 foot) spacing. The pull of the Weyerhaeuser Way was strong within Dr. Strub and he decided to install a permanent 1/10th acre circular plot to insure survival over time (of course it is widely accpeted that Weyerhaeuser trees never die). Dr. Strub established his plot center such that a tree appeared on exactly every integer point of the cartesian plane, except at plot center (he removed this tree). Of course Weyerhaeuser trees are all cylicndrical in shape and all grow at the same rate of growth. At plot center, as the trees grow, it becomes harder and harder to see outside of the plot circle. What will be the trees' DBH when the plot center (0,0) first loses its line of sight outside of the plot circle*? 

Please give your answer as a decimal number with 10 significant digits. 

*Note: Since the trees are all cyclindrical in shape and have the same rate of growth (only diameter growth matters) the height at which "line of sight" is viewed is arbitrary. For example, assume that all trees are 4.5' tall, and only exhibit diameter growth.

Figure 1. Example of a 1/200th acre circular plot (radius = 8.33) and a ray entering (plot center).


SOLUTION: The solution should be sent to Dr. Strub at strub@mcfns.com.

Paste winners

Year Winner Affiliation Challenge
2013 Quang Cao





  • Quantitative Management
  • Plantation Management
  • Computational Forestry
  • Inventory Issues
  • Growth and Yield Modeling
  • Data and databases
  • Harvest scheduling
  • GIS applications

Important dates

  • Call for Abstracts: Aug 10, 2014
  • Abstract Deadline: Oct 1, 2014
  • Early registration deadline: Oct 1, 2014
  • Hotel reservation: Oct 19, 2014