At Southgate Mall, mattresses are sold only at Mattress Madness. Every mattress at Mattress Madness is on sale at a 2...

Naz on July 16, 2015

Okay let's diagram this argument:

"At Southgate Mall, mattresses are sold only at Mattress Madness."

So: If a mattress is sold at Southgate Mall, it is from Mattress Madness.

P1: MSGM ==> MM
not MM ==> not MSGM

"Every mattress at Mattress Madness is on sale at a 20 percent discount."

So: If it is a mattress from Mattress Madness, then it is on sale at a 20 percent discount.

P2: MM ==> 20%D
not 20% D ==> not MM

"So every mattress for sale at Southgate Mall is on sale at a 20 percent discount."

C: MSGM ==> 20%D
not 20%D ==> not MSGM

Here we have a valid positive transitive argument. We can connect P1 to P2 like so: MSGM ==> MM ==> 20%D to conclude: MSGM ==> 20%D, which is exactly what our conclusion is.

Now, let's diagram answer choice (C):

"All the food in Diane's apartment is in her refrigerator."

So: If it is food in Diane's apartment, then it is in her refrigerator.

P1: FDA ==> R
not R ==> not FDA

"Diana purchased all the food in her refrigerator within the past week."

So: If it is food in Diane's refrigerator, then it was purchased within the past week.

P2: R ==> PPW
not PPW ==> not R

"Therefore, she purchased all the food in her apartment within the past week."

So: If it is food in Diane's apartment, it was purchased within the past week.

C: FDA ==> PPW
not PPW ==> not FDA

Answer choice (C), just like in the argument, is a valid positive transitive argument. We can connect P1 to P2 like so: FDA ==> R ==> PPW to conclude: FDA ==> PPW, which is exactly what our conclusion is.

Thus, answer choice (C) is the correct answer.

Hope that clears things up! Please let us know if you have any other questions.

franco on November 7, 2017

I don't understand the difference between answers C and D they seem so similar

Mehran on November 13, 2017

Hi @franco, thanks for your post. This is a Parallel Reasoning question. Let's first look closely at the argument in the stimulus, so we can be sure that we parallel it correctly.

At Southgate Mall:
P: Mattresses are sold only at Mattress Madness.
M ==> MM
P: Every mattress at Mattress Madness is on sale at a 20% discount.
MM ==> 20%
C: So every mattress for sale at Southgate Mall is on sale at a 20% discount.
M ==> 20%
This is a valid transitive argument.

Answer choice (C):
P: All the food in Diane's apartment is in her refrigerator.
F ==> R
P: Diane purchased all the food in her refrigerator within the past week.
R ==> past week
C: Therefore, she purchased all the food in her apartment within the past week.
F ==> past week
This is also a valid transitive argument.

Answer choice (D):
P: The only food in Diane's apartment is in her refrigerator.
F ==> R
P: D purchased all the food in her refrigerator within the past week.
R ==> past week.
C: Therefore, all the food she purchased within the past week is in *her apartment.*
past week ==> apt

This is not parallel to the reasoning in either the stimulus or answer choice (C).

Hope this helps!