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

Redeem

Target Test Prep · GMAT

Choose how you want to prepare

Learn live with an expert or move at your own pace. Every option includes the complete TTP study system.

★★★★★5.0559 reviews
GMATLiveTeach Starts Oct 17
Chris Peckover, Target Test Prep GMAT expert
LIVE ONLINE CLASSES

Get Ready for GMAT Test Day Faster with Live Online Classes

with Chris Peckover, 100th-Percentile GMAT Scorer

Oct 17 · Chris Peckover
Sat · 11:00 AM to 2:00 PM ET
Oct 20 · Chris Peckover
Tue, Thu · 8:00 to 10:00 PM ET
Oct 25 · Josh Braslow
Sun · 1:00 to 4:00 PM ET
Included
40 hours of live online classes + 6 months of TTP OnDemand
  • Attend the first class for free
  • Every class is recorded, so you never fall behind
View classes & enroll
Limited seats availableTarget Test Prep
EALiveTeachOnDemand 5 seats left Start anytime
EXECUTIVE ASSESSMENT

Target Test Prep EA OnDemand

Self-paced EA prep. Study on your schedule.

Logan Thompson
EXECUTIVE ASSESSMENT

Sep 6 to Dec 6, 2026

with Logan Thompson

165+ EA score guarantee
$05-day trial no automatic billing
Schedule
Sun · 9:30 AM to 12:30 PM ET
Included
40 hours of live online classes plus six months of access to the complete TTP EA OnDemand course.
  • 165+ EA Score Guarantee
  • 4,100+ Quant, Verbal, and Integrated Reasoning practice questions
  • 400+ hours of in-depth video lessons
  • 3,000+ step-by-step video solutions
View EA class & enroll Start free 5-day trial
Limited cohort · enrollment openTrial includes full course accessTarget Test Prep
GMATOnDemand Start anytime
SELF-PACED MASTERCLASS

Target Test Prep GMAT OnDemand

Complete access from day one. Study on your schedule.

715+ score guarantee
$0to start then $127/mo
  • Personalized study plan and analytics
  • Thousands of lessons and practice questions

Compare the format, schedule, and included access before enrolling. Prices and seat counts shown reflect the supplied offer details.

Of the 60 families in a certain neighborhood

Expert replies
by Soumita Ghosh » Fri Feb 22, 2013 10:59 am
Of the 60 families in a certain neighborhood, 38 have a cat. How many of the families in this neighborhood have a dog?

(1) 28 of the families in this neighborhood have a cat but not a dog
(2) The number of families in the neighborhood who have a dog and a cat is the same as the number of families who have neither a cat nor a dog.

OA B

I have found that statement 1 alone is insufficient.

I am facing problem regarding calculation in statement B even though I know that statement 2 alone is sufficient.

Kindly see my calculation thoroughly and let me know where I am doing mistake.

I have solved this in matrix form.

Please find the attachment

I found the number of the families in this neighborhood have a dog which is 22(highlighted in yellow)through this way. So I found statement 2 is sufficient.


When I am calculating this below way I also able to find the answer:

D = no of the families have a dog.

60 = 38+D-X+X
or, D = 22.

But my problem is when I am solving this below way I am not able to solve X.

60 = 38-X+X+X+22-X (refer my above matrix in order to find how I got this expression)

Then I do not know how to solve.

I know I am doing here some mistake. Please point out my mistake in this calculation.
Attachments
matrix.docx
Please find the attachment
(12.6 KiB) Downloaded 141 times
Join the discussion
Source: — Data Sufficiency |

by ceilidh.erickson » Fri Feb 22, 2013 1:04 pm
Your use of the matrix was perfect here, and it allowed you to get to the right answer. Why are you also trying to solve algebraically? There's no need to solve twice!

If I understand what you're saying, you're able to solve for D (number of dogs) algebraically, but that you're not able to solve for X. But why are you trying to solve for X? The question is asking about the number of dogs, so finding D is sufficient. It doesn't matter what X is at all. In fact, consider these scenarios:

Here's one possible solution for X:

Image


But here's another scenario that also works:

Image


Statement 2 is not sufficient to solve for X, but who cares?! It's sufficient to solve for D, and that's all we need.
Ceilidh Erickson
EdM in Mind, Brain, and Education
Harvard Graduate School of Education
Join the discussion