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October 2015 LSAT
Which one of the following must be true?
on March 14, 2020
Please explain answer
Please explain answer.
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on March 14, 2020
The answer to "must be true" questions is most often found in the initial setup. The game requires us to determine the schedule of 5 students - G H J K L who work exactly two shifts for a total of ten shifts over five days.
1 ___ ___ ___ ___ ___ G __ G H or J
2 ___ ___ ___ ___ ___ LL J H
M T W Th F
The rules tell us that:
(1) No student works both shifts of any day, so we must have two different students each day.
(2) L works the second shift on two consecutive days.
This rule tells us we must have LL combination somewhere in our schedule for the second shift.
(3) On two nonconsecutive days, G works the first shift.
(4) K works on T & F.
(6) H & J work on the same day as each other at least once.
(6) G & L never work on the same day as each other.
This is a restrictive rule, let's think about possible combinations,
G K ___ H G
__ L L J K
__ K G H G
L L __ J K
H G __ __ G
J K L L K
Note that H & J shifts are interchangeable for each of these scenarios.
Now let's look at the answer choices:
(A) G does not work on T.
Incorrect, scenario 3 allows G to work on T.
(B) H does not work on W.
Incorrect because there are no restrictions on when H's second shift must be. One of his shifts must be with J but his second shift is a free variable and could be on any open day.
(C) J does not work on T.
Correct. In all three scenarios, K & L or G & K must work on T.
(D) J does not work on Th.
Incorrect. Scenario (1) allows J to work on Th.
(E) L does not work on T.
Incorrect. Scenario 2 allows L to work on T.
Let me know if you have any other questions.