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.

Percent Change

Expert replies
by Rudy414 » Fri Mar 22, 2013 1:35 pm
The average of three distinct positive integers x, y, and z is 64. If a new number d is add, will the percent increase exceed 13%?

1) d is twice the value of one of the original numbers

2) d is half the value of the largest of the original numbers

B

I actually got the answer right, but I am not sure if my math is correct or if I just got lucky.

Here is how I solved it:

1. (x+y+z)/3 = 64 -> x+y+z = 192
2. 13% of 192 is approximately 23. So, in order for d to be at least a 13% increase, d > 23
3. The most extreme number combinations are 189+1+2, in which case (for statement 2) d=94.5, and 63+64+65, in which case d=32.5. Since both are greater than 23, the percent increase is greater than 13%.

Does this make sense or am I missing something?

Thank you
Join the discussion
Source: — Data Sufficiency |

by Anju@Gurome » Fri Mar 22, 2013 2:25 pm
Rudy414 wrote:The average of three distinct positive integers x, y, and z is 64. If a new number d is add, will the percent increase exceed 13%?

1) d is twice the value of one of the original numbers
2) d is half the value of the largest of the original numbers
"percent increase" of what? The sum or the average?

If it is percent increase of the sum
The new sum must be 64*3*(1.13) ≈ 217
Hence, for the percent increase of sum to exceed 13%, d must be greater than or equal to (217 - 192) = 25

Statement 1: Let us assume x = 1, y = 2, and z = 189
Now,
  • if d = 2x ---> d = 2 < 25
    but
    if d = 2z ---> d = 378 > 25
Not sufficient

Statement 2: The minimum possible value of the largest of the original three integers is 65. As 65/2 = 32.5 > 25, the half of the largest of the original three integers will be always greater than 25.
Hence, d > 25

Sufficient
[spoiler]
The correct answer is B.[/spoiler]
Anju Agarwal
Quant Expert, Gurome

Backup Methods : General guide on plugging, estimation etc.
Wavy Curve Method : Solving complex inequalities in a matter of seconds.

§ GMAT with Gurome § Admissions with Gurome § Career Advising with Gurome §
Join the discussion

by Anju@Gurome » Fri Mar 22, 2013 2:31 pm
If it is percent increase of the average
The new sum must be 64*(1.13)*4 ≈ 289
Hence, for the percent increase of sum to exceed 13%, d must be greater than (289 - 192) = 97
So, the question is whether d > 97 or not.

Statement 1: Let us assume x = 1, y = 2, and z = 189
Now,
  • if d = 2x ---> d = 2 < 97
    but
    if d = 2z ---> d = 378 > 97
Not sufficient

Statement 2: The maximum possible value of the largest of the original three integers is 189. As 189/2 = 94.5 < 97, the half of the largest of the original three integers will be always less than 97.
Hence, d < 97

Sufficient

The correct answer is B.
Anju Agarwal
Quant Expert, Gurome

Backup Methods : General guide on plugging, estimation etc.
Wavy Curve Method : Solving complex inequalities in a matter of seconds.

§ GMAT with Gurome § Admissions with Gurome § Career Advising with Gurome §
Join the discussion

by Rudy414 » Fri Mar 22, 2013 2:59 pm
It didn't say the percent increase of the average or the sum. I suppose the question is talking about the percent change of the average since it gave the original average, as opposed to giving the original sum.

Either way, I just wanted to make sure my logic was sound, and it sounds like you confirmed it. I just need to be careful of the scope (i.e., solving for the sum or the average).

Thank you.
Join the discussion

by hemant_rajput » Sat Mar 23, 2013 9:31 am
Hi Rudy,
"percent increase" of what? The sum or the average?
The point that Anju made is quite important. The question you posted is ambiguous; As every GMAT experts says don't practice from books which doesn't comply with GMAT Standards because it will not only throw your skills in wrong direction but also it is possible that you may pick wrong habits(grammatical mistakes) while solving those questions.

Believe me, I've done that mistake for a long time and I can tell you it was not worth it.
I'm no expert, just trying to work on my skills. If I've made any mistakes please bear with me.
Join the discussion