Which one of the following must be true about any acceptable product code?

Anita on May 8, 2018

C is the correct answer here. If the second digit is twice the first, then the only combinations that work are:

1 - 2

OR

2 - 4

Both put 2 before 3, as it has to be either the first or second digit, in every code created. 4 does not have to be before 3 in every code, even if it may be in some.

Take for example:

2 4 0 1 3

This satisfies that the second slot is twice the first, and the third slot is less than the fifth. In this case, 3 is last.

Does that help?

appozernick on June 5, 2019

Hi, how come the statement made below stating "4 does not have to be before 3 in every code" is correct, if our set up only allows for 1-2 and 2-4?

Ravi on June 7, 2019

Hey there,

We know an employee generates a series of 5-digit codes.

The digits used can be 0, 1, 2, 3, or 4.

Each digit is used exactly once.

The 2nd digit is double the 1st digit's value

The 3rd digit is less than the 5th digit.

1 2 _ _ _
2 4 _ _ _

The first and second digits have to be either 1 and 2 or 2 an 4
because those are the only two pairs of numbers are double/half of
each other, which allows us to satisfy the rule about the 2nd and 1st
digits.

Using our rules, we can solve for all possibilities of this game.
There are 6 possibilities for the game:

1 2 3 0 4
1 2 0 3 4
1 2 0 4 3

2 4 1 0 3
2 4 0 1 3
2 4 0 3 1

As we see, 4 doesn't have to be before 3 in every code. There are two
code patterns in which 4 comes after 3.

Hope this helps. Let us know if you have any other questions!

appozernick on June 11, 2019

Thank you, I have another question, but it's about your introduction to logical reasoning video.


Premise: anyone named sue is a girl
Premise: x is named sue
Therefore, x is a girl


You said is an invalid argument, however, I fail to see it as such. I can see it as an unsound argument.

Thoughts?

Victoria on June 11, 2019

Hello,

Technically, yes, the argument can be considered to be valid but unsound. For the most part, when attempting logical reasoning questions, we must assume that the premises are true. In other words, we are simply determining whether the argument is valid or not based on the assumption that the premises are true. In this way, we are addressing half of the requirements for an argument to be considered sound (whether it is valid or not) while assuming that the premises are true.

The purpose of this example in the logical reasoning video is to introduce the possibility that the LSAT may include false premises in some of its logical reasoning passages. This is rare and will generally occur only in cases where a premise is obviously false as in this example where the premise that "anyone named Sue is a girl" is proven to be clearly false when we consider the popular song "A Boy Named Sue." False premises are not frequently introduced by the LSAT; the purpose of this example was simply to ensure that you keep in the back of your mind that there is always the possibility that one of the premises may be false.

Overall, regardless of terminology, the goal of logical reasoning questions is to assess your ability to understand an argument and determine whether its conclusion can logically be drawn or not. To successfully address these questions, you must always assume that the premises are true - unless they are are glaringly false - and, from there, determine whether the argument is valid or not.

I hope this is helpful. If you need any further clarification or have other questions please let us know!