October 2004 LSAT Section 3 Question 13

# Which one of the following could be an accurate list of the discoverers of the five sites, listed in the order in whi...

1 Reply

Ravi on May 16 at 07:52PM

@jamesteemartin,I'm sorry to hear that. The team is working diligently on adding as

many video explanations as possible. Feel free to direct any support

related issues to our support staff by tapping "support" from the left

menu or by calling 855.483.7862 ext. 2 Monday-Friday 9am-6pm PT. I'll

also let them know that you'd like a video for this one.

In the meantime, I'm happy to provide a written explanation for this game.

We know there are 5 archeological sites, and that each was discovered

by F, G, or O. We also know that each of these sites dates from the

8th, 9th, or 10th centuries.

_ _ _ _ _

_ _ _ _ _

1 3 5

The bottom row will be filled with F, G, or O, and the top row will be

filled with 8, 9, or 10 (denoting the centuries).

Rule 1 says the 2nd site dates from the 9th century

1) 2nd site - >9th

_ 9 _ _ _

_ _ _ _ _

Rule 2 says O didn't discover the 4th or 5th site. This means that

either F or G discovered the 4th or 5th site.

2) 4th and 5th - >F/G

_ 9 _ _ _

_ _ _ F/G/F/G

Rule 3 says G discovered 1 site, and it's from the 10th century

3) G - >10 and G ex. 1

The contrapositive for this rule is if the site doesn't date from the

10th century, then G didn't discover it. This means that for site 2, F

or O discovered it since it's from the 9th century

Rule 4 says if a site dates from the 8th century, then it was dicovered by O

4) 8 - >O

The contrapositive for this rule is that if O didn't discover a site, then

the site doesn't date to the 8th century.

We know that sites 4 and 5 were discovered by F or G, so now we know

that these sites are from the 9th or 10th century.

_ 9 _ 9/10 9/10

_ F/O_ F/G F/G

The 5th rule tells us that the 3rd site dates from a more recent

century than either the 1st or 4th site

3rd more recent than either 1st or 4th

We know more recent centuries have higher numbers (e.g., the 10th

century is more recent than the 9th century), so in looking at our

board, we see that the 4th site is from the 9th or 10th century. We

know the 3rd has to be more recent, so the only way that can be true

is if the 3rd site is from the 10th century and the 4th is from the

9th century. This also means that the 1st site has to be from the 8th

or 9th century.

8/9 9 10 9 9/10

_ F/O _ F/G F/G

What other inferences can we make with the rules we have? Let's see.

For the first site, we know that it's from the 8th or 9th century.

From rule 3, we know that if a site isn't from the 10th century, G

didn't discover it, so F or O discovered site 1. We also know from

earlier that if we see a G, then there has to be a 10 with it. Since

site 4 has a 9, this means that site 4 has F, not G.

8/9 9 10 9 9/10

F/O F/O _ F F/G

Question 13 says, "Which one of the following could be an accurate

list of the discoverers of the five sites, listed in the order in

which the sites are visited?"

(A) Oliphant, Oliphant, Gallagher, Oliphant, Ferrara

(B) Gallagher, Oliphant, Ferrara, Ferrara, Ferrara

(C) Oliphant, Gallagher, Oliphant, Ferrara, Ferrara

(D) Oliphant, Oliphant, Gallagher, Ferrara, Gallagher

(E) Ferrara, Oliphant, Gallagher, Ferrara, Ferrara

We know G goes only once, so (D) is out. We also know that G can only

go in 3 or 5, so (B) and (C) are out. This leaves us with (A) and (E).

In looking at our board, we know that F is in site 4, and (A) has O in

site 4, so it's out. This leaves us with (E) as the correct answer.

Question 14 says, "If exactly one of the five sites the tour group

visits dates from the tenth century, then which one of the following

CANNOT be a site that was discovered by Ferrara?"

(A) the site visited first

(B) the site visited second

(C) the site visited third

(D) the site visited fourth

(E) the site visited fifth

We now know that site 5 is a 9 since there's only one 10. Also, we

have to have 1 G, so the G has to go in site 3.

8/9 9 10 9 9

F/O F/O G F F

We now know that site 5 is a 9 since there's only one 10. We know that

site 3 can't be discovered by F, and this is exactly what (C) says, so

it's the correct answer.

Question 15 says, "Which one of the following could be a site that

dates from the eighth century?"

(A) the site visited first

(B) the site visited second

(C) the site visited third

(D) the site visited fourth

(E) the site visited fifth

8/9 9 10 9 9/10

F/O F/O _ F F/G

In looking at our board, only the first site could be from the 8th

century, so (A) is the correct answer choice.

Question 16 says, "Which one of the following is a complete and

accurate list of the sites each of which CANNOT be the site discovered

by Gallagher?"

(A) third, fourth, fifth

(B) second, third, fourth

(C) first, fourth, fifth

(D) first, second, fifth

(E) first, second, fourth

8/9 9 10 9 9/10

F/O F/O _ F F/G

We know G can't be in 1, 2, and 4 from our game board. This leaves us

with (E), which is the correct answer choice.

Question 17 says, "The tour group could visit at most how many sites

that were discovered by Ferrara?"

(A) one

(B) two

(C) three

(D) four

(E) five

8/9 9 10 9 9/10

F/O F/O _ F F/G

The rules never tell us that O has to even appear in the game, so we

can put in F as many times as possible as long as we have one spot for

G

8/9 9 10 9 9/10

F F G F F

This leaves us with 4 Fs and 1 G, so (D) is the correct answer choice.

I hope this helps. Let us know if you have any more questionsâ€”we're

here to help!