February 1993 LSAT Section 2 Question 9

# On Wednesday Doctor Yamata could be scheduled to

Replies

Irina on November 17, 2019

@calixtefatou,What do you mean by email explanation?

I will forward your request for video explanation to our curriculum team. Please let us know if you'd like a written explanation in the meantime.

Thanks.

Fatou on November 17, 2019

Sorry autocorrect got me. I meant a video explanation of the game, but I will take a written one too.Thank you

Irina on November 17, 2019

@calixtefatou,The game requires us to determine the schedule of doctor's activities over a 5 day period - M, T, W , F and S - note that the game skips Th. The doctor performs four types of activities - lecturing (L); operating (O), treating patients (T) and conducting research (R). Each working day she performs one activity in the morning and one in the afternoon,

AM ___ ___ ___ ___ ___

PM ___ ___ ___ ___ ___

M T W F S

The following rules apply:

(1) She performs operations on exactly three mornings.

O = 3 AM

AM ___ ___ ___ ___ ___ 3x O

PM ___ ___ ___ ___ ___

M T W F S

(2) If she operates on Monday, she does not operate on Tuesday.

O(M) -> ~O(T)

We can infer that if she operates on Tuesday, then she cannot operate on Tuesday.

O(T) -> ~O (M)

In other words, it is impossible for her to operate on both M and T.

(3) She lectures in the afternoon on exactly two consecutive calendar days.

This rule tells us that she could lecture either on MT, TW, or FS - these are the only options for two consecutive calendar days.

AM ___ ___ ___ ___ ___ 3x O

PM ___ ___ ___ ___ ___ LL

M T W F S

(4) She treats patients on exactly one morning and exactly three afternoons.

AM ___ ___ ___ ___ ___ 3xO T

PM ___ ___ ___ ___ ___ LL 3xT

M T W F S

/T /T

This rule tells us that out of five afternoons, two consecutive afternoons are L and the rest are T. This allows us to infer that either W or F afternoon or both must be T, since we cannot have LL on W & F (nonconsecutive calendar days)

(5) She conducts research on exactly one morning.

AM ___ ___ ___ ___ ___ 3xO T R

PM ___ ___ ___ ___ ___ LL 3xT

M T W F S

/T /T

(6) On Saturday, she neither lectures nor performs operations.

AM ___ ___ ___ ___ T/R 3xO T R

PM ___ ___ ___ ___ T LL 3xT

M T W F S

/T /T ~L

~O

This rule allows us to infer that she must teach on Saturday afternoon and either teach or do research on Saturday morning.

This rule also allows us to infer that she must lecture either on MT or TW afternoons as these are the only consecutive calendar days remaining, thus she must definitely teach on Friday afternoon and she must definitely lecture on Tuesday and either on M or W.

AM ___ ___ ___ ___ T/R 3xO T R

PM L/T L L/T T T LL 3xT

M T W F S

~L

~O

This rule further allows us to conclude that since she operates on three mornings and cannot operate on S and could only operate on either M or T, not both, we can conclude that she must definitely operate on W and F and on either M or T, and teach or do research on the remaining day that she does not operate on.

AM O/T/R O/T/R O O T/R 3xO T R

PM L/T L L/T T T LL 3xT

M T W F S

This is our final setup diagram. Let's look at the questions:

Question 1 asks us which of the following must be a day on which Doctor Yamata lectures?

We can see from the setup diagram that she must lecture on Tuesday afternoon (B).

Question 2 asks us on Wednesday, doctor Yamata could be scheduled to

We can see that she must operate in the morning and either lecture or teach in the afternoon )(C).

Question 3 asks us which of the following statements must be true.

We can see that she must lecture on T and either M and W, and operate on W and either M or T, therefore she must definitely lecture on one of the days on which she operates (E). Just to illustrate why there must an overlap, consider all the potential scenarios:

AM T/R O O

PM L L T

M T W

AM O T/R O

PM T L L

M T W

Question 4 asks us if Doctor Yamata operates on Tuesday, then her schedule could be:

If she operates on T, we can conclude that she must either do research or teach on M morning.

AM T/R O O O T/R

PM L/T L L/T T T

M T W F S

We already know that she must treat patients on F and S afternoon, thus we can eliminate (A) and (C). We know that she treats patients on only one of the mornings, eliminating (B). And we know that she must operate on W morning, eliminating (D). (E) is the only possible schedule of treating patients that complies with all the rules.

Question 5 asks which of the following is a pair of days on both of which Doctor Yamata must treat patients?

We can see from our initial setup, that she must treat patients on F and S afternoons (E).

Let me know if this helps and if you have any further questions.