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No man left with his own wife, as then they would have been on the ground the same length of time.
An Armstrong leaving at 8:45 would be incompatible with a Borman leaving at 8:55, and the same applies to an Armstrong leaving at 8:55 with a Collins leaving at 9:10, as that would also create situations of more than one person being on the ground for the same length of time.
This leaves only four orders of leaving for a given set of A, B and C of a given gender. Listed, with the corresponding number of minutes on the ground, they are:
A(45) B(35) C(30) C(30)
C(40) C(40) A(55) B(45)
B(60) A(70) B(60) A(70)
The only pair of these lists that doesn't contain any duplicate is that consisting of the two middle lists: BCA and CAB.
In the latter list, C has a shorter time than C on the former list, as does A on the latter vs. A on the former. So CAB is the order of the men and BCA is the order of the women:
Mrs. Borman and Mr. Collins left at 8:45
Mrs. Collins and Mr. Armstrong left at 8:55
Mrs. Armstrong and Mr. Borman left at 9:10
Based on Enigma No. 1477, "In transit", by Susan Denham, New Scientist, 19 January 2008. |
