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 →

geese!!

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Legendary Member
Posts: 1083
Joined: Wed Feb 24, 2010 9:38 pmFollowed by: 14 members
Thanked: 127 times
by gmat_perfect » Mon Jun 14, 2010 1:58 am
A total of 30 percent of the geese included in a certain migration study were male. If some of the geese migrated during the study and 20 percent of the migrating geese were male, what was the ratio of the migration rate for the male geese to the migration rate for the female geese?
[Migration rate for geese of a certain GMAT = (number of geese of that GMAT migrating) / (total number of geese of that GMAT)]

A. 1/4
B. 7/12
C. 2/3
D. 7/8
E. 8/7
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
User avatar
Master | Next Rank: 500 Posts
Posts: 392
Joined: Sun May 16, 2010 2:42 amFollowed by: 10 members
Location: Bangalore, India
Thanked: 116 times
GMAT Score:770

by albatross86 » Mon Jun 14, 2010 2:13 am
Let total number of geese be G
Therefore, number of geese that are male = 30% of G = 0.3*G

Assuming a goose can be either a goose or a gander (hehe) this means that 70% of the total number of geese are female
So number of female geese = 0.7*G

Let the number of geese that migrated be M
Therefore, number of male migrating geese = 20% of M = 0.2*M

Therefore number of female migrating geese = 0.8*M


Using the formula for migration rate provided:

Migration rate for male geese = 0.2*M / 0.3*G

Migration rate for female geese = 0.8*M / 0.7*G

Therefore ratio of the 2 rates = 0.2*M * 0.7*G / 0.3*G *0.8*M

= 14/24

= 7 /12

Pick B
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Master | Next Rank: 500 Posts
Posts: 362
Joined: Fri Oct 02, 2009 4:18 amFollowed by: 1 member
Thanked: 26 times

by indiantiger » Mon Jun 14, 2010 7:52 am
Let the total number of geese be n.

Male population becomes 30n/100 as given in the question
female becomes = 1- 30n/100 = 70n/100

Let the migrating population be x

male population migrating = 20x/100
female population migrating = 80x/100

male ratio = (20x/100)/(30n/100) = 2x/3n
female ratio = (80x/100)/(70n/100) = 8x/7n

overall ratio = 2x/3n / 8x/7n = 2/3 * 7/8 = 7/12 (B)

Please correct me if I have done any step wrong.
"Single Malt is better than Blended"
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
GMAT Instructor
Posts: 1302
Joined: Mon Oct 19, 2009 2:13 pmFollowed by: 164 members
Location: Toronto
Thanked: 539 times
GMAT Score:800

by Testluv » Tue Jun 15, 2010 12:00 am
When dealing with percentages of an unspecified value, many people find it quicker/easier to pick numbers than to use algebra.

When dealing with a percent of an unknown value, pick 100. So, let the number of geese be 100. 30 are males while 70 are females.

Some unknown number of geese migrated, and 20% of them were male. Suppose that 50 geese migrated. Then, 10 were males while 40 were females. So 10 out of 30 male geese migrated while 40 out of 70 female geese migrated.

So the migration rate for male geese is 1/3 while the migration rate for female geese is 4/7. The ratio is (1/3)/(4/7) or 7/12.

Choose B.
Kaplan Teacher in Toronto
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1