Last visit was: 25 Nov 2024, 14:05 It is currently 25 Nov 2024, 14:05

Close

GRE Prep Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GRE score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel
Verbal Expert
Joined: 18 Apr 2015
Posts: 30024
Own Kudos [?]: 36397 [0]
Given Kudos: 25929
Send PM
avatar
Director
Director
Joined: 03 Sep 2017
Posts: 518
Own Kudos [?]: 703 [0]
Given Kudos: 0
Send PM
Verbal Expert
Joined: 18 Apr 2015
Posts: 30024
Own Kudos [?]: 36397 [0]
Given Kudos: 25929
Send PM
avatar
Director
Director
Joined: 03 Sep 2017
Posts: 518
Own Kudos [?]: 703 [0]
Given Kudos: 0
Send PM
Re: The value of P if V = 20 and T = 32 [#permalink]
Using the formula, then we have that column A is equal to \(P=\frac{8}{5}k\) and column B is equal to \(T=\frac{780}{k}\). Comparing those two quantities and simplifying we finally reach a comparison between \(k^2\) and 487.5. Given that k can be whatever constant, we can't say which one of the two is the greatest, thus answer is D!
avatar
Director
Director
Joined: 09 Nov 2018
Posts: 505
Own Kudos [?]: 133 [0]
Given Kudos: 0
Send PM
Re: The value of P if V = 20 and T = 32 [#permalink]
IlCreatore wrote:
Using the formula, then we have that column A is equal to \(P=\frac{8}{5}k\) and column B is equal to \(T=\frac{780}{k}\). Comparing those two quantities and simplifying we finally reach a comparison between \(k^2\) and 487.5. Given that k can be whatever constant, we can't say which one of the two is the greatest, thus answer is D!


Just an example:
If k=0, a=0 b=undefined
k=1 makes a=1.6 b=780
so answer D.
Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Own Kudos [?]: 12198 [0]
Given Kudos: 136
Send PM
Re: The value of P if V = 20 and T = 32 [#permalink]
1
Carcass wrote:

This question is part of GREPrepClub - The Questions Vault Project




For a certain quantity of a gas, pressure P, volume V, and temperature T are related according to the formula PV = kT, where k is a constant.

Quantity A
Quantity B
The value of P if V = 20 and T = 32
The value of T if V = 10 and P = 78



QUANTITY A: The value of P if V = 20 and T = 32
Take given formula, PV = kT, and plug in values to get: P(20) = k(32)
Divide both sides by 20 to get: P = 32k/20
Simplify to get: P = 8k/5

QUANTITY B: The value of T if V = 10 and P = 78
Take given formula, PV = kT, and plug in values to get: (78)(10) = kT
Divide both sides by k to get: (78)(10)/k = T
Simplify to get: T = 780/k

So, we have:
QUANTITY A: 8k/5
QUANTITY B:780/k


Let's TEST some possible values of k

Try k = 1
In this case, we get:
QUANTITY A: 8k/5 = (8)(1)/5 = 8/5
QUANTITY B:780/k = 780/1 = 780
In this case, QUANTITY B IS GREATER

Try k = 1000
In this case, we get:
QUANTITY A: 8k/5 = (8)(1000)/5 = some number greater than 1
QUANTITY B:780/k = 780/1000 = some number less than 1
In this case, QUANTITY A IS GREATER

Answer: D

Cheers,
Brent
avatar
Intern
Intern
Joined: 02 Oct 2018
Posts: 31
Own Kudos [?]: 11 [0]
Given Kudos: 0
Send PM
Re: The value of P if V = 20 and T = 32 [#permalink]
The answer is D.
In the first case it becomes P=1.6k whereas in the second case it becomes 780/k.

Since we don't know k we can't determine the answer.
Prep Club for GRE Bot
Re: The value of P if V = 20 and T = 32 [#permalink]
Moderators:
GRE Instructor
84 posts
GRE Forum Moderator
37 posts
Moderator
1111 posts
GRE Instructor
234 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne