February 1993 LSAT
Section 2
Question 10
Which one of the following statements must be true?
Reply
Victoria on September 3, 2020
Hi @Anna2020,Happy to help!
We know that Dr. Y works five days of the week: M, T, W, F, and S.
On these days, she performs four different activities: L, O, P, and R.
She performs exactly one activity in the morning and exactly one activity in the afternoon.
AM: _ _ _ _ _
PM: _ _ _ _ _
M T W F S
Now let's go through our conditions.
Rule 1 - Dr. Y performs O exactly three mornings during the week.
Rule 2 - If Dr. Y performs O on M, she does not perform O on T.
OM --> Not OT
OT --> Not OM
Rule 3 - Dr. Y does L in the afternoon on exactly two consecutive calendar days.
Rule 4 - Dr. Y treats P on exactly one morning and exactly three afternoons.
Rule 5 - Dr. Y conducts R on exactly one morning.
Rule 6 - Dr. Y neither does L nor performs O on Saturday.
This means that Dr. Y can only conduct R or treat P on Saturday.
We now know the activities which must take up all 10 slots of Dr. Y's time during the week. We just don't know what order they go in.
Morning Activities: O O O P R
Afternoon Activities: L L P P P
We do know that Dr. Y cannot perform O on S and Rule 2 tells us that she cannot perform O on both M and T. Therefore, we have two options for Dr. Y's mornings.
Option 1
AM: O R/P O O P/R
M T W F S
Option 2
AM: R/P O O O P/R
M T W F S
We also know that Dr. Y does L in the afternoon on exactly two consecutive days which cannot be Saturday. Therefore, we have three options.
Option 1
PM: L L P P P
M T W F S
Option 2
PM: P L L P P
M T W F S
Option 3
PM: P P L L P
M T W F S
We are looking for the answer choice which MUST be true.
Answer choice (C) could be true, but it does not have to be true. Why? Because pairing Option 1 AM and Option 1 PM gives us a schedule where Dr. Y does not conduct R on a day where she treats P. Notice that there is nothing that says Dr. Y must perform two different activities each day. Therefore, there is no reason why Dr. Y cannot treat P all day Saturday.
AM: O R O O P
PM: L L P P P
M T W F S
The only day on which Dr. Y conducts R is a day when she does L. Notice that this meets all of our conditions:
1) Dr. Y performs O on M, W, and F mornings.
2) Dr. Y performs O on M and does not perform O on T.
3) Dr. Y does L on M and T afternoons.
4) Dr. Y treats P on F morning and on W, F, and S afternoons.
5) Dr. Y conducts R on T morning.
6) Dr. Y only treats P on S; she neither does L nor performs O on this day.
On the other hand, answer choice (E) must be true because it is impossible to design a schedule where Dr. Y does not L on the same day that she performs O.
Starting with AM Option 1, O and L overlap on:
PM Option 1 - Monday
PM Option 2 - Wednesday
PM Option 3 - Wednesday and Friday
Now moving to AM Option 2, O and L overlap on:
PM Option 1 - Tuesday
PM Option 2 - Tuesday and Wednesday
PM Option 3 - Wednesday and Friday
Hope this helps! Please let us know if you have any further questions.