Carl Grimaldi, ABM Inc., IT Analyst
Edgar Casson, Chiptech, Director
Joshua Graves, Reed Right, CEO
Alan Clarkson, Blue Teeth, Accountant
Thomas Fielder, Lantel, Developer
To solve this teaser, you first need to determine who shared which room with whom. Three delegates shared the triple and two shared the twin. The CEO shared with the businessman from ABM in one room and Edgar shared with the Developer in the other (1). Since Grimaldi is either the IT Analyst or the CEO (3) and the CEO shared with the IT Analyst, Grimaldi is in the same room as whoever is the CEO, IT Analyst and ABM delegate although Grimaldi could have been one of these people. Edgar did not share with Carl (6) so Carl is in the same bedroom as, and possibly is, the CEO, IT Analyst, Grimaldi and/or the ABM delegate. Grimaldi and Thomas were in different rooms so Thomas shared a room with Clarkson (5) and the Reed Right delegate was in a different room to Thomas. At this stage we know:
Reed Right delegate
Since the Chiptech delegate shared with the Lantel delegate (7), both of these must have been in room 2 otherwise there would be four delegates in room 1 which is not possible.
Now this has been ascertained, the puzzle can be solved:
The CEO shared with the IT Analyst so the IT Analyst must work for ABM (Clues 1 and 8) so the CEO must work for Reed Right. Since Grimaldi does not work for Reed Right, he must be the IT Analyst. Clarkson, Fielder and Casson are in room 2 so the CEO must be Graves. Graves is not Edgar (1), Thomas (4), Carl (IT Analyst) or Alan (2) so must be Joshua. Clarkson is not Thomas (5), Edgar (6), Carl or Joshua (in room 1) so must be Alan. The Director does not work for Lantel or Blue Teeth (2), Reed Right or ABM (room 1) so must work for Chiptech. This is not Graves or Grimaldi (room 1), Clarkson (2) or Fielder (11) so must be Casson. Since Graves; first name is Joshua, Casson must be Edgar (6). Alan Clarkson does not work for Reed Right or ABM (room 1); Lantel (5) or Chiptech so must work for Blue Teeth. Since he is not the Developer (12) he must be the Accountant. This leaves Thomas Fielder who is the Developer for Lantel.
Today's brain teaser courtesy of Braingle.com.