BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem
TTP OnDemand GMAT Video Course
Featured Course

Target Test Prep GMAT OnDemand

Scott Woodbury-Stewart’s private virtual classroom — 400 hours of master-class video lessons for the GMAT Focus Edition.

  • 715+ score guarantee — highest in the industry (99th percentile)
  • 52 chapters · 1,500+ lessons · 4,000+ practice questions
  • 400 hours of video · 1,500+ instructor-led HD smartboard lessons
  • 300,000+ students accepted to Harvard, Stanford, Wharton, Booth & Sloan & more
  • 24/7 live support + weekly Zoom office hours with GMAT instructors
  • TTP AI Assist — 24/7 AI-powered virtual tutor for instant help
  • 1,200+ flashcards + AI-powered study assistant & daily calendar
  • OnDemand, LiveTeach & GMAT Bootcamp formats available
  • Also: GRE, SAT Math & Executive Assessment courses
  • MBA Admissions Consulting now available
  • 🏆 2025 EdTech Breakthrough Award: Test Prep Solution Provider of the Year
  • 200,000+ students served
  • 5-day free trial — $0 to start, no auto-billing, cancel anytime
★★★★★ 5.0 (559 reviews)
130-pt guarantee
$0 to start then $127/mo
Start Free 5-Day Trial Read 559 Reviews →

If xy=4, x/y=36, for positive numbers x and y, y=?

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Elite Legendary Member
Posts: 3991
Joined: Fri Jul 24, 2015 2:28 amFollowed by: 37 members
Location: Las Vegas, USA
Thanked: 19 times
by Max@Math Revolution » Mon Jun 27, 2016 5:41 pm
If xy=4, x/y=36, for positive numbers x and y, y=?
A. 1/2
B. 2
C. 1/3
D. 3
E. 1/6

*Answer will be posted in 2 days.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
Master | Next Rank: 500 Posts
Posts: 199
Joined: Sat Apr 26, 2014 10:53 amFollowed by: 4 members
Thanked: 16 times
GMAT Score:780

by 800_or_bust » Tue Jun 28, 2016 10:56 am
Max@Math Revolution wrote:If xy=4, x/y=36, for positive numbers x and y, y=?
A. 1/2
B. 2
C. 1/3
D. 3
E. 1/6

*Answer will be posted in 2 days.
Given: (1) xy = 4; and (2) x/y = 36

From (2), solve for x by multiplying both sides of the equation by y: x = 36y

Now substitute this into the first equation: (36y)y = 4

36y^2 = 4
y^2 = 1/9
y = +/- 1/3

But we're told from the prompt that y must be positive, so +1/3 is the only possible solution. Answer choice: C
800 or bust!
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members
Location: Vancouver, BC
Thanked: 5254 times
GMAT Score:770

by Brent@GMATPrepNow » Tue Jun 28, 2016 11:41 am
Max@Math Revolution wrote:If xy=4, x/y=36, for positive numbers x and y, y=?

A. 1/2
B. 2
C. 1/3
D. 3
E. 1/6
Another alternate is to check the answer choices.

A) y = 1/2
Since xy = 4, we can conclude that x = 8
If y = 1/2 and x = 8, then x/y = (8)/(1/2) = 16.
NOT GOOD, x/y is SUPPOSED to equal 36
ELIMINATE A

B) y = 2
Since xy = 4, we can conclude that x = 2
If y = 2 and x = 2, then x/y = 2/2 = 1.
NOT GOOD, x/y is SUPPOSED to equal 36
ELIMINATE B

C) y = 1/3
Since xy = 4, we can conclude that x = 12
If y = 1/3 and x = 12, then x/y = (12)/(1/3) = 36.
GREAT! x/y is SUPPOSED to equal 36
Answer: C
Brent Hanneson - Creator of GMATPrepNow.com
Image
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Elite Legendary Member
Posts: 3991
Joined: Fri Jul 24, 2015 2:28 amFollowed by: 37 members
Location: Las Vegas, USA
Thanked: 19 times

by Max@Math Revolution » Wed Jun 29, 2016 7:13 pm
If we substitute in x=4/y, from 4/y^2 =36, we get y^2=1/9. Hence, y=1/3. Thus, the correct answer is C.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1