Why exactly is answer b incorrect?

A walk-thru of Q 4.

This answers Anna's question ("why is choice 'B' wrong?").

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Can anyone load this video? As I understand it choice b does in fact meet the exact requirements...

T F S

G H
H G G ...... This is the only possibility
For both movie G and H
As to suffice 2 H's and
3 G's due to the fact Saturday cannot have G and H but must have G because G is in all three as given. Therefore H must be played on both thursday and Friday in order to meet the requirement of H 2 times. Now to address L.... 1L is required and can potentially be played on Thursday or Saturday but not Friday due to the fact that G is played and on Friday G and L cannot both play...
In conclusion, choice B "exactly two are shown Friday" is in fact always true... Show G then H are definitely played and L cannot play

B Co,

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Here's a text-based explanation:

The Stem Rule says we need:
G x3
H x2
L x1

So, first thing we know is that "G" must be shown on each day.
But we don't know when "G" will be shown on a given day (1st, 2nd, or 3rd).
So let's look at the other Rules and see if we can figure it out.

Rule 1: we know H must be last. So "G" cannot be.
MAYBE the "L" is shown on Thursday, maybe not. We don't know.
Since there are no other Rules that affect Thursday's showings, we can go ahead and put "G" first.

Thu: G, L?, H
(Note that we have a question mark on "L")


Now for Friday:
We know that "G" must be shown.
And we know that "G" and "L" cannot both be shown.
So "G" will be shown, and it must be last (Rule 2).
And it seems that the second "H" might also be shown on Friday.
Let's mark it with a "?" for now.

Fri: H?, G


Now let's do Saturday:
Again, G must be shown.
Since G is shown, it must be shown last, and H cannot be shown (Rule 3).
So now we're down to two possibilities: Only G is shown, or G and L are shown.

Sat: L?, G

*Note that we now know that H must be shown on both Thursday and Friday, since it must be shown twice, and it cannot be shown Saturday.


Let's put 'em all together:

Thu: G, L?, H
Fri: H?, G
Sat: L?, G

What can we glean from our model? Well, it looks like we have two options:

Thu: G, L, H
Fri: H, G
Sat: G

-or-

Thu: G, H
Fri: H, G
Sat: L, G


Why is choice "B" wrong?
Option 1 has only ONE film shown on Saturday.
That's the reason choice "B" is wrong. It is NOT true that you must have two films shown on Saturday.


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