Which one of the following is a sequence, from first to last, in which the nonhostile witnesses could be interviewed?

Irina on November 30, 2019

@farnoushsalimian,

This is a linear game that requires us to determine the order of witness interviews - M through S.
Two days of the week must be reserved for interviewing hostile witnesses and nonhostile witnesses must be interviewed exactly once for a full morning or afternoon - Q R U X Y Z. This tells us that we have 4 days out of 6 to interview 6 nonhostile witnesses and two available slots per day. The only witnesses who are interviewed simultaneously with each other are Q and R. This rule tells us that we actually only need 5 slots to interview all six witnesses over four days.

m
a
M T W Th F S

The following rules apply:

(1) X must be interviewed Th morning.

m X
a
M T W Th F S

This means that one or two (Q &R ) of the nonhostile witnesses must be interview Th afternoon since hostile witnesses always take up the full day.

(2) Q must be interviewed sometime before X.

We know that Q &R are interviewed together, so we can conclude that:

Q & R > X

and Q &R pair must be either on M T or W.

(3) U must be interviewed sometime before R

We can infer that U is interviewed before Q & R interview, though it is possible for them to still be interviewed on the same day as long as U is interviewed in the morning & Q &R in the afternoon.

U > Q & R > X

(4) Z must be interviewed at some time after X and at some time after Y.

X > Z
Y

or the complete order is U > Q &R > X
> Z
Y
This rule tells us that the earliest Z could be interviewed is Thursday afternoon assuming that Y is interviewed on one of the previous days. Could Z be interviewed on Friday or later?

Z could only be interviewed on Friday or later if Y is interviewed on Thursday afternoon or later and U, Q &R are interviewed on the same day - either on Monday or Wednesday - otherwise, we would have no two full consecutive days left for hostile witnesses.

Scenario 1:

m /U /U X Y/Z Y/Z
a /QR H /QR /Y
M T W Th F S

In this scenario, Tuesday must necessarily be reserved for hostile witnesses as well as Monday or Wednesday.

Scenario 2:

If Z is interviewed on Thursday afternoon instead, then we have to place U, Q &R and Y on either M, T, or W - since we need three interview slots, they will necessarily take at least 1.5 days and at most all three days, leaving Friday and Saturday as the only possible two full consecutive days for hostile witnesses.


m X
a Z H H
M T W Th F S

/U /Y / Q & R

Note that Y is a free variable and could come before U or after Q &R or in between U & Q & R .

With these scenarios in mind, let's look a the questions.

Question 1 asks us which of the following is a possible sequence of interviews?

Looking back at the order above U > Q &R > X
> Z
Y
we can eliminate (A), (B), (C), and (E), leaving (D) - U Y Q&R X Z as the only sequence that complies with all the rules.

Question 2 asks which of the following is an acceptable schedule of witnesses for Tuesday morning, Tuesday afternoon and Wednesday morning?

m X
a
M T W Th F S

We know that X is on Thursday morning, so we can eliminate (C) right away. We know that Q &R must be interviewed together, so we can eliminate (A) & (B).

Looking back at our scenarios above we know that the earliest Z could be placed per rule (4) is Thursday afternoon, thus we can eliminate (E), leaving us with (D) as the correct answer:

m U none X
a Y
M T W Th

Question 3 asks if Y is interviewed at some point after X, which of the following must be a day reserved for interviewing hostile witnesses?

Looking back at our two scenarios above, we see that if Y is interviewed after X, Tuesday must be reserved for hostile witnesses (B)

m /U /U X Y/Z Y/Z
a /QR H /QR /Y
M T W Th F S

Question 4 asks if R is interviewed at some time after Y, which one of the following must be a day reserved for interviewing hostile witnesses.

Again, looking at the scenarios above, we see that the only scenario when R is interviewed at some point after Y is when Z is on Thursday and Fr and Saturday are reserved for hostile witnesses (E).


m X
a Z H H
M T W Th F S

/U /Y / Q & R

Question 5 asks if on Wednesday afternoon and on Monday the attorney conducts no interviews, which of the following must be true?

This scenario tells us that hostile witness interviews must be on Fr Sat and we are in scenario (2) above where Z is interviewed on Thursday afternoon.

m N X
a N N Z H H
M T W Th F S

We can thus conclude that Z must be interviewed before Friday (E).

Question 6 asks if Z is interviewed on Saturday morning, which of the following could be true?

If Z is interviewed on Saturday, we are in scenario (1).

m U X /Y Z
a QR H H /Y /Y
M T W Th F S

We know that Y must be interviewed either on Thursday afternoon, Friday morning or afternoon, and Tuesday must be reserved for hostile witnesses - thus we can eliminate (B), (D) and (E). R must be interviewed before X, thus we can eliminate (C), leaving (A) is the only possible option - Tuesday and Wednesday are both reserved for hostile witnesses.

Let me know if this makes sense and if you have any other questions.

zachmorley2 on November 30, 2020

You accidentally included a comma after Q on answer choice C.

on December 10, 2020

How were you able to infer that interviewing nonhostile witnesses will always take up a full day? It obviously says a time slot must fill a complete afternoon or morning slot, but I am confused how that means the entire day must be filled?

on December 10, 2020

What is wrong with this as an example of meeting the rules without both time slots on a nonhostile witness day being filled?

M Tu W Th F S
M U QR X Z
A Y

on December 10, 2020

Sorry, but the format of my answer was messed up after submitting so it no longer looks like it follows the rules.