June 2007 - Sec 1 - Game 1 - Q2

Video Transcript:

0:08
Moving to Question 2, Which one of the following must be true about any acceptable
0:13
product code?
0:15
Let's take a look here at (A), digit 1 appears in some position before digit 2.
0:21
Well, looking at our previous work from Question 1, we see digit 1 after digit 2 so (A) does
0:30
not follow, doesn't have to be true, so (A) would be out. Again, coming from Question
0:36
1.
0:37
(B), the first digit appears in some position before the third digit. Again, coming directly
0:44
from our previous work in Question 1, we see the third digit appear before the first digit
0:52
or the first digit appear after the third digit, so again B doesn't have to be true
0:58
coming directly from Question 1.
1:01
(C), the second digit appears in some position before the third digit. And if you notice
1:08
in our 2 scenarios, in scenario 1 digit 2 is second and 3 would come somewhere in 3,
1:17
4 or 5, which clearly means that 2 appears before 3. In scenario 2, 2 is first so clearly
1:26
3 must appear after 2.
1:29
So you notice in both of our scenarios, 2 appears before 3 so (C) must be true and (C)
1:38