Gigi's Logic Puzzles

This Week's Exciting Puzzle: Confusion in the Exam Bank

This puzzle appeared in Volume 77, Issue 5 (June 26, 1998) of mathNEWS,
and was co-authored by Andrea Knowles.


This issue's problem deals with some confusion in the MathSoc office. When the new file folders came in, the office workers labelled them for the exam booklets. However, when they were putting the exam booklets into the file folders, they didn't put a single one in the correct file folder! There are now four rows of four file folders out on the desk and it's up to you to put them in the right spot. The exam booklets that are mixed up are for the following courses: MATH 135, MATH 136, MATH 137, MATH 138, MATH 145, MATH 146, MATH 147, MATH 148, MATH 235, MATH 237, MATH 245, MATH 247, CS 134, STAT 230, STAT 231, and PMATH 360. Can you figure out where each exam booklet is and which file folder they're in?


  1. No two exam booklets were merely switched. If the file for MATH 135 contains the booklet for PMATH 360, then the file folder for PMATH 360 does not contain the exam booklet for MATH 135.
  2. The leftmost file folder in the third row from the top was labelled MATH 145, but contained the booklet for STAT 230.
  3. The exam booklet for MATH 237 was found in the file folder for MATH 135.
  4. The first sign that something was wrong with the filing system was discovered when a student asked for the exam booklet for MATH 245 (the file found right above the file labelled MATH 145) which contained the exam booklet for MATH 135.
  5. On the bottom row from left to right were the exam booklet for MATH 245, the exam booklet for MATH 147, the file folder labelled MATH 146 and the file folder labelled MATH 137.
  6. The file folder in the upper left corner (which wasn't labelled STAT 230) contained the exam booklet for STAT 231.
  7. The file folder containing MATH 138 (which was not to be found in the second row from the top) was labelled MATH 148 which scared some 1B student studying for their midterm as when they asked for MATH 138 they received an exam booklet not of that course.
  8. The file folder labelled MATH 138 actually had the exam booklet for MATH 245.
  9. the file folder containing MATH 146 wasn't in the second row from the top. 10. On the top row, in some order, were the exam booklet for MATH 135, the file folder for STAT 230, the file folder for CS 134 and the file folder immediately above the one containing the exam booklet for MATH 136.
  10. The file folder labelled MATH 147, which actually contained CS 134, was not on the end of any row.
  11. The students looking at exams during lunch were quite surprised to see the exam booklets for MATH 148 and MATH 145 when they asked to see MATH 137 and MATH 136 (not necessarily respectively).
  12. MATH 137 was in the file folder labelled MATH 235, the file folders immediatedly above and below were labelled MATH 237 and MATH 247 in some order.
  13. The file folder containing MATH 136 was immediately above the one containing MATH 148 which in turn was immediately above the one containing PMATH 360.


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