Q23

[theonlyrij]

Hi,

For 23, I wasn't sure why the correct answer was B- lap 2.

I see that A and D relate to the same position in the line, but I still dont understand why Jacobson could have been in either of those.

Please explain.

Thanks!

[bbirdwell]

There are two relevant constraints:

1. We have to have OJ occur at least once.

2. O's first lap has to be after M's.

From #2 we learn that O cannot go first. By consequence of the game's organization, this also means that O cannot go 6th.

Adding this inference to #1 above means that J will never be second, nor 7th.

[GabeR312]

Don't we also know that J cannot go first? O has to come before J, and since O can't go first aren't we able to eliminate J front his also?

I would seem that there are 2 correct answers here. can you please explain why A is wrong?

[ohthatpatrick]

Sure. Rule 4 says that "AT LEAST ONE of the two J's is immediately after an O".

We need OJ to happen at least once, but that doesn't mean that all J's are immediately after all O's.

If we put J in lap 1, he'd also be lap 6.

J __ __ __ __ J __ __ __ __

Can you think of a way to get at least one OJ?

It would have to be 5/6, which seems potentially doable:
J __ __ __ O J __ __ __ O

Here's a complete scenario that follows all the rules:
J K M L O J K M L O