Small errors corrected in our LP/IP examples

Two small errors in our LP examples have been corrected thanks to remarks of a student:

Errors corrected:

• Portfolio planning (LP): The constraints for the 3-month construction loans (earning 6% over the 3-month period) should contain references to three cells (months) instead of 2. Cells B45 en B46 in the MS Excel file corrected.
• Recycling waste (LP): Every week, the company receives a € 30,000 grant for treating the materials, if at least half of the available volume is treated for each material. >= instead of <= constraints in cells B40, C40, D40 en E40.

These corrections are now solved thanks to the remark of Pieter Verbruggen (Vlerick Business School (Belgium)).