Q13 - Most people who are skilled banjo players

[783874728]

I think the stimuli means that the banjo needs more skill to master than guitar, so I chose B, can someone explains this?

[maryadkins]

This question isn't about what's harder, banjo or guitar. It's testing your knowledge of overlapping groups. In other words, does being told that most X are Y mean that most Y are X? (No.) That sort of thing.

This kind of thing comes up on the LSAT a lot, so it's important to learn. The Logical Reasoning strategy guide covers it in the section on formal logic.

On to the question, itself.

We are told that most people who are good at banjo are good at guitar. That means that over 50% of good banjo players are also good at guitar.

Then we're told that most good guitar players aren't great banjo players. So that means the people who are good at both? They compose less than 50% of guitar players, but more than 50% of banjo players. So what does THIS mean?

Well, we're talking about a set group of people: the people good at both. We can pick a random number, say, 50 people are good at both. If those 50 players are more than half of banjo players but less than half of guitar players, what does that mean about the total number in each group? It means the group of banjo players is smaller than 100 (so 99 or fewer), and that the group of guitar players is bigger than 100 (101+). It also means that the leftover banjo players who aren't good at guitar is a smaller number (49 or fewer) than the leftover guitar players who aren't good at banjo (51 or more).

(A) is wrong because we know there are 51 or more people who play only guitar well.

(B), as I said above, makes it about difficult of learning the instrument. This is not what this question is testing nor can we infer it.

(C) is the same way.

(D) is correct.

(E) is not true.

Tricky question! Hope this helps.

[Bradklingener]

Confused as to why the two groups need to be seen as having an equal number of players. If there are 100 skilled banjo players and only 5 skilled guitar players the answer doesn't seem to make sense anymore. We have to make an assumption that there is an equal amount of skilled players in each group? Its asking for what must be true, but the correct answer doesn't really accomplish that for me. If anyone can shed some light on this it would be greatly appreciated.

[mishawakajess]

I'll attempt to explain how I got the answer using a different approach than the one Mary gave above, which will hopefully answer your question.

First consider a set of skilled banjo players ("B"). Everyone that occupies the physical white space within the B (......................) parentheses below is B. A subset "G" is also skilled at guitar, and occupies the space to the right of the / and to the left of the ) parenthesis.

B (......../.................G..)

Next, consider an equal set of G, again, all the white space within the G (......................) parentheses below. There is a subset "~B" occupying the space to the right of the / and to the left of the ) parenthesis.

G (......../...............~B..)

Now, in your mind, consider the size of space that B can claim relative to the size of space that G can claim.

The space that can be claimed by B includes the entire space within the parentheses in the B (......................) as well as the smaller space between the ( and / in G (......./...............~B..).

Next, see that the space that can be claimed by G includes the entire space within the parentheses in G (......................) as well as the larger space between the / and ) in B (......../.................G..) the first row.

As you can see through the comparison, the total space that can be claimed by G is bigger.

In answer to your question, we can also vary the sizes of the spaces to test this.

Say that the group of B is comparatively way larger, as diagrammed below. The total space that can be claimed by G is *still* larger than the total space that can be claimed by B.
B (......./...................G..)
G (......................../................................................~B..)

Or, say the group of guitar players is comparatively way smaller. G still claims more space than B!
B (......./...................G..)
G (.../......~B..)

Because most of B will also be G, there will always be a significant amount of B that can be claimed by G. Because most of G will NOT be B, there will always be a significant amount of G that CANNOT be claimed by B. Thus G will always be able to claim more space in total, since it can always claim all of its space as well as most of the space in B's population.

Once you try to visualize it, it becomes a way clearer problem!

[LukeM22]

I think I've figured out a pretty simple way of approaching this:

1) A majority of B (skilled banjo players) are also skilled guitar players: B+G

51% of B = B+G

2) A majority of G (skilled guitar players) are not also skilled B banjo players: B+G

51% of G= - B+G; B+G=49% (or even less)

51 % of B (or more) = B+G

49% of G (or less) = B+G

At the very least, 51% of B is equivalent to 49% of G.

G> B

[ohthatpatrick]

I'll throw my own way into the fray, for what it's worth.

There are a certain number of people in the world who are skilled at both guitar and banjo.
You can pick a variable for them or pick any number. Let's say that there are 1,000 people in the world who are good at both.

The 1st sentence says that those 1000 people are more than half of all skilled banjo players.
The 2nd sentence says that those 1000 people are less than half of all skilled guitar players.

If 1000 is more than 1/2 of skilled banjo players, then they can total at most 1,999
If 1000 is less than 1/2 of skilled guitar players, then they must total at least 2,001

[LenB401]

This question isn't about what's harder, banjo or guitar. It's testing your knowledge of overlapping groups. In other words, does being told that most X are Y mean that most Y are X? (No.) That sort of thing.

This kind of thing comes up on the LSAT a lot, so it's important to learn. The Logical Reasoning strategy guide covers it in the section on formal logic.

On to the question, itself.

We are told that most people who are good at banjo are good at guitar. That means that over 50% of good banjo players are also good at guitar.

Then we're told that most good guitar players aren't great banjo players. So that means the people who are good at both? They compose less than 50% of guitar players, but more than 50% of banjo players. So what does THIS mean?

Well, we're talking about a set group of people: the people good at both. We can pick a random number, say, 50 people are good at both. If those 50 players are more than half of banjo players but less than half of guitar players, what does that mean about the total number in each group? It means the group of banjo players is smaller than 100 (so 99 or fewer), and that the group of guitar players is bigger than 100 (101+). It also means that the leftover banjo players who aren't good at guitar is a smaller number (49 or fewer) than the leftover guitar players who aren't good at banjo (51 or more).

(A) is wrong because we know there are 51 or more people who play only guitar well.

(B), as I said above, makes it about difficult of learning the instrument. This is not what this question is testing nor can we infer it.

(C) is the same way.

(D) is correct.

(E) is not true.

Tricky question! Hope this helps.

I wanted to know if this method was wrong so I don't use it again, I remember this from the LR book on conditionals.
Most A's are B's
Most B's are not A's

I deduced it to be Some A's are B's
Some Banjo players are guitar players and realized the answer choice available was the opposite meaning if some banjo players are guitar players, they are. more guitar players than banjo players.

[smiller]

I deduced it to be Some A's are B's

It's excellent to notice the similarity between this and the method mentioned in the LR guide. However, it doesn't apply to this question.

When considering overlap between three groups like A, B, and C, we can make the kind of inference similar to the one that you describe. If most As are Bs, and most As are Cs, we can infer that some Bs are Cs.

For example, if the stimulus stated that most skilled banjo players are skilled guitar players, and most skilled banjo players like Steve Martin's music, we can infer that some skilled guitar players like Steve Martin's music.

However, the question that we're discussing here is very different because we're dealing with people who are skilled banjo players and people who are not skilled banjo players. Rather than A, B, and C, we're dealing with A, B, and "not A." Also, we don't have two "most" statements about the same group the way we do in the example above. Because of this, we aren't able to infer the same kind of overlap between the most statements.

To go even further, your statement that "Some A's are B's" isn't a new inference. It's actually repeating what we already know from the single statement "Most A's are B's." Remember that "most" means more than 50%. "Some" as it's used on the LSAT simply means "more than zero." Let's use some emojis as an example:



It's true that most of the emojis are smileys (more than 50%). It's also true that some of them are smileys (more than zero). The statement that "some of the emojis are smileys" doesn't provide any new information that isn't already included in the knowledge that most are smileys.