Because we know from the first condition that A cannot finish in the first place, B in the second, etc., we can easily list all the remaining combinations:
BADEC BAECD BCAED BCDEA BCEAD BDAEC BDEAC BDECA BEACD BECAD
BEDAC BEDCA CABED CADEB CAEBD CDAEB CDEAB CDEBA CEABD CEBAD
CEDAB CEDBA DABEC DAEBC DAECB DCAEB DCBEA DCEAB DCEBA DEABC
DEACB DEBAC DEBCA EABCD EADBC EADCB ECABD ECBAD ECDAB ECDBA
EDABC EDACB EDBAC EDBCA
The first condition also eliminates combinations containing one or more of the following pairs of consecutive contestants:
AB BC CD DE
This is what is left:
BEDAC BEDCA CABED CADEB CAEBD CDAEB CDEAB CDEBA CEABD CEBAD
or:
BDAEC BECAD BEDAC BEDCA CAEBD CEBAD CEDBA DAECB DCAEB DCBEA
DCEBA EADCB ECBAD EDACB EDBAC
The second condition requires that exactly two of the contestant finish in the order DAECB.
D A E C B
BDAEC
BECAD
BEDAC
BEDCA *
CAEBD * *
CEBAD
CEDBA
DAECB * * * * *
DCAEB * *
DCBEA *
DCEBA * *
EADCB * *
ECBAD
EDACB * *
EDBAC
This leaves the following six combinations:
CAEBD DCAEB DCEBA EADCB EDACB
We need to find the combination in which two disjoint pairs of students predicted to finish consecutively actually do so. The pairs are: DA AE EC CB
The solution is EDACB, where the two pairs are DA and CB
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