A set has exactly five consecutive positive integers starting with 1.What is the percentage decrease in the average when the greatest number is removed from the set?
A)5
B)8.5
C)12.5
D)15.2
E)16.6
The OA is E
How should I do this PS question? Should I calculate both averages and then compare them?
5-Day Free Trial
5-day free, full-access trial TTP
Available with Beat the GMAT members only code
MORE DETAILS
A set has exactly five consecutive positive
This topic has expert replies
GMAT/MBA Expert
-
Jay@ManhattanReview
- GMAT Instructor
- Posts: 3008
- Joined: Mon Aug 22, 2016 6:19 am
- Location: Grand Central / New York
- Thanked: 470 times
- Followed by:34 members
The given set is {1, 2, 3, 4, 5}. Since this is an equally spaced set, its average would be the middle-most number = 3.Vincen wrote:A set has exactly five consecutive positive integers starting with 1.What is the percentage decrease in the average when the greatest number is removed from the set?
A)5
B)8.5
C)12.5
D)15.2
E)16.6
The OA is E
How should I do this PS question? Should I calculate both averages and then compare them?
After removing the greatest number 5, we get the set {1, 2, 3, 4}. This is also an equally spaces set, but the number of elements is even, thus, the average would be the average of the two middle-most numbers, 2 and 3. Thus, the new average = (2 + 3)/2 = 2.5.
The percentage decrease in the average when the greatest number is removed from the set = [(3 - 2.5) / 3]*100% = [0.5 / 3]*100% = 16.67%.
The correct answer: E
Hope this helps!
-Jay
Download free ebook: Manhattan Review GMAT Quantitative Question Bank Guide
_________________
Manhattan Review GMAT Prep
Locations: New York | Vienna | Kuala Lumpur | Sydney | and many more...
Schedule your free consultation with an experienced GMAT Prep Advisor! Click here.
-
Matt@VeritasPrep
- GMAT Instructor
- Posts: 2630
- Joined: Wed Sep 12, 2012 3:32 pm
- Location: East Bay all the way
- Thanked: 625 times
- Followed by:119 members
- GMAT Score:780
Initial set: 1, 2, 3, 4, 5
Initial average: 3
New set: 1, 2, 3, 4
New average: 2.5
Decrease = (2.5 - 3)/3 = -.5/3 = -1/6 ≈ 16.67%
Initial average: 3
New set: 1, 2, 3, 4
New average: 2.5
Decrease = (2.5 - 3)/3 = -.5/3 = -1/6 ≈ 16.67%
GMAT/MBA Expert
-
Scott@TargetTestPrep
- GMAT Instructor
- Posts: 7247
- Joined: Sat Apr 25, 2015 10:56 am
- Location: Los Angeles, CA
- Thanked: 43 times
- Followed by:29 members
The original average = (1 + 2 + 3 + 4 + 5)/5 = 3.Vincen wrote:A set has exactly five consecutive positive integers starting with 1.What is the percentage decrease in the average when the greatest number is removed from the set?
A)5
B)8.5
C)12.5
D)15.2
E)16.6
The OA is E
How should I do this PS question? Should I calculate both averages and then compare them?
The new average = (1 + 2 + 3 + 4)/4 = 2.5
(2.5 - 3)/3 x 100 = -0.5/3 x 100 = -1/6 x 100 ≈ -16.7
We see that the average is decreased by approximately 16.7%.
Answer: E
Scott Woodbury-Stewart
Founder and CEO
[email protected]
See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews
GMAT/MBA Expert
-
[email protected]
- Elite Legendary Member
- Posts: 10392
- Joined: Sun Jun 23, 2013 6:38 pm
- Location: Palo Alto, CA
- Thanked: 2867 times
- Followed by:511 members
- GMAT Score:800
Hi All,
We're told that a set has exactly five CONSECUTIVE positive integers starting with 1. We're asked for the percentage decrease in the average when the greatest number is removed from the set. This question requires the use of the Percent Change Formula:
Percent Change = (New - Old)/(Old) = (Difference)/(Original
The original set of numbers is 1, 2, 3, 4, 5, so the average of that set is (1+2+3+4+5)/5 = 15/5 = 3
Once we remove the greatest number, we're left with 1, 2, 3, 4, so the average of that new set is (1+2+3+4)/4 = 10/4 = 2.5
The Percent Change would be (2.5 - 3)/3 = .5/3 = 1/6 = 16 2/3%
Final Answer: E
GMAT assassins aren't born, they're made,
Rich
We're told that a set has exactly five CONSECUTIVE positive integers starting with 1. We're asked for the percentage decrease in the average when the greatest number is removed from the set. This question requires the use of the Percent Change Formula:
Percent Change = (New - Old)/(Old) = (Difference)/(Original
The original set of numbers is 1, 2, 3, 4, 5, so the average of that set is (1+2+3+4+5)/5 = 15/5 = 3
Once we remove the greatest number, we're left with 1, 2, 3, 4, so the average of that new set is (1+2+3+4)/4 = 10/4 = 2.5
The Percent Change would be (2.5 - 3)/3 = .5/3 = 1/6 = 16 2/3%
Final Answer: E
GMAT assassins aren't born, they're made,
Rich
