Can you solve the dragon jousting riddle? - Alex Gendler
-
0:07 - 0:09After centuries of war,
-
0:09 - 0:12the world’s kingdoms
have come to an agreement. -
0:12 - 0:17Every five years, teams representing
the elves, goblins, and treefolk -
0:17 - 0:22will compete in a grand tournament
of dragon jousting. -
0:22 - 0:25Every team will face
each of the others once. -
0:25 - 0:30The kingdom whose team wins the most
matches will rule all of Center-Realm -
0:30 - 0:32until the next tournament.
-
0:32 - 0:34To prevent any outside meddling,
-
0:34 - 0:38the games are to be conducted
in absolute secret -
0:38 - 0:40except for a group of wizards
who will make sure -
0:40 - 0:46nobody uses enchantments, hexes,
or spells to cheat. -
0:46 - 0:49You’ve been given the extremely
important job of recording the scores -
0:49 - 0:52for the first inaugural tournament.
-
0:52 - 0:55But the opening celebrations
get a bit out of control, -
0:55 - 0:57and when you wake up,
-
0:57 - 1:00you realize the games
are already underway. -
1:00 - 1:04Fortunately, no one has noticed
your absence so far. -
1:04 - 1:07However, you need to get up to speed
quickly; -
1:07 - 1:09if your boss,
the head tournament official, -
1:09 - 1:14finds out you’ve been sleeping on the job,
you’ll lose your head. -
1:14 - 1:15After weighing your options,
-
1:15 - 1:20you decide to offer your life’s savings
to one of the regulation wizards -
1:20 - 1:21in return for the information,
-
1:21 - 1:24giving him your blank scorecard
to fill out. -
1:24 - 1:28But before he can finish,
your boss walks into the tent. -
1:28 - 1:31You barely manage to hide the scorecard
in time, -
1:31 - 1:34and the wizard excuses himself.
-
1:34 - 1:35Your boss chuckles.
-
1:35 - 1:38“Hope you didn’t believe anything
Gorbak’s been saying— -
1:38 - 1:42he’s been cursed to tell only lies,
even in writing. -
1:42 - 1:45Anyway, can you believe how low-scoring
the tournament’s been? -
1:45 - 1:47Every team has played at least once,
-
1:47 - 1:52yet not a single match with
a combined score of more than five hits! -
1:52 - 1:55Anyhow, I’ll be back in a minute
to review your scorecard.” -
1:55 - 1:57You laugh along,
-
1:57 - 2:00and when he leaves you look
at the partially completed card, -
2:00 - 2:04now knowing every single number
on it is wrong. -
2:04 - 2:06You’ve only got one chance
to save yourself, -
2:06 - 2:10so what’s the real score of each match?
-
2:10 - 2:17Pause now to figure it out for yourself.
-
2:17 - 2:21The incredible thing about this riddle
is that you can reach the solution -
2:21 - 2:25despite an almost complete lack
of correct information. -
2:25 - 2:28And that’s possible because
knowing that something is false -
2:28 - 2:32is meaningful information
in its own right. -
2:32 - 2:36The first key is to realize that no team
will play more than two matches, -
2:36 - 2:39since there are only two other teams.
-
2:39 - 2:42So if the elves didn’t actually play
one match, -
2:42 - 2:45and the goblins didn’t actually play two,
-
2:45 - 2:50the truth must be that elves played two
and goblins played one. -
2:50 - 2:52For the elves to have played two matches,
-
2:52 - 2:55they must’ve faced each of the other teams
once. -
2:55 - 3:00And since goblins have only played
one match so far— against the elves— -
3:00 - 3:04that means the match between goblins
and treefolk has not occurred yet. -
3:04 - 3:08We know it’s false that the treefolk tied
zero matches, -
3:08 - 3:12which means their bout
against the elves must’ve tied. -
3:12 - 3:15We also know that the elves won
at least one match, -
3:15 - 3:20and since they tied against the treefolk,
they must have beaten the goblins. -
3:20 - 3:23But can we figure out the actual scores?
-
3:23 - 3:26Let’s start with the elf-treefolk tie.
-
3:26 - 3:29Because no more than five total hits
were scored, -
3:29 - 3:33the final tally must’ve been
0-0, 1-1, or 2-2. -
3:33 - 3:36But the treefolk must’ve scored
some hits, -
3:36 - 3:40and it’s false that they only had one hit
scored against them. -
3:40 - 3:43The only option that leaves is 2-2.
-
3:43 - 3:46In the match between elves and goblins,
-
3:46 - 3:49the goblins must’ve scored
at least one hit. -
3:49 - 3:53And the elf score must be 2 or more
for them to have won the match. -
3:53 - 3:58This leaves only a few possibilities
that add up to 5 or less. -
3:58 - 4:02The elves couldn’t have scored three,
so that eliminates these two. -
4:02 - 4:07And their total hits scored
across both matches can’t add up to six, -
4:07 - 4:09so this one’s out too.
-
4:09 - 4:12So the score must’ve been 2-1.
-
4:12 - 4:13With one match remaining,
-
4:13 - 4:17you’ve managed to save your job—
and your neck. -
4:17 - 4:18Gorbak the wizard may have lied,
-
4:18 - 4:22but your deductive skills
quickly evened the score.
- Title:
- Can you solve the dragon jousting riddle? - Alex Gendler
- Speaker:
- Alex Gendler
- Description:
-
View full lesson: https://ed.ted.com/lessons/can-you-solve-the-dragon-jousting-riddle-alex-gendler
After years of war, the world’s kingdoms have come to an agreement. Every five years, teams representing the elves, goblins, and treefolk will compete in a grand tournament of dragon jousting. You have the important job of recording the scores for the inaugural tournament. But, you overslept and the games are already underway. Can you figure out the real score of each match? Alex Gendler shows how.
Lesson by Alex Gendler, directed by Artrake Studio.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TED-Ed
- Duration:
- 04:23
Elise Haadsma approved English subtitles for Can you solve the dragon jousting riddle? | ||
Elise Haadsma accepted English subtitles for Can you solve the dragon jousting riddle? | ||
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