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A set has exactly five consecutive positive integers

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A set has exactly five consecutive positive integers

by swerve » Fri May 25, 2018 1:28 pm

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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. 16.4

The OA is E.

Please, can anyone explain this PS question? I can't get the correct answer. I need help to solve it. Thanks.
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by [email protected] » Fri May 25, 2018 4:14 pm
Hi swerve,

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

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by Brent@GMATPrepNow » Fri May 25, 2018 4:43 pm
swerve 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. 16.4
What's the source of this question?
It seems very un-GMAT-like to "round" 16 2/3 to 16.4 without some kind of language that suggests we're looking for the best APPROXIMATE answer.
Brent Hanneson - Creator of GMATPrepNow.com
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by Scott@TargetTestPrep » Tue May 07, 2019 5:34 pm
swerve 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. 16.4
The original average = (1 + 2 + 3 + 4 + 5)/5 = 3.

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

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by Scott@TargetTestPrep » Tue May 07, 2019 5:34 pm
swerve 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. 16.4
The original average = (1 + 2 + 3 + 4 + 5)/5 = 3.

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]

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See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews

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