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#### Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here. # The average (arithmetic mean) of a set of n test scores is 8  Question banks Downloads My Bookmarks Reviews Important topics
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The average (arithmetic mean) of a set of n test scores is 8 [#permalink]
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Question Stats: 88% (01:01) correct 11% (01:21) wrong based on 44 sessions
The average (arithmetic mean) of a set of n test scores is 80. The average (arithmetic mean) of these n scores together with a score of 85 is 81.

 Quantity A Quantity B $$n$$ $$5$$

A)The quantity in Column A is greater.
B)The quantity in Column B is greater.
C)The two quantities are equal.
D)The relationship cannot be determined from the information given.

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[Reveal] Spoiler: OA

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Re: The average (arithmetic mean) of a set of n test scores is 8 [#permalink]
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Expert's post
Carcass wrote:
The average (arithmetic mean) of a set of n test scores is 80. The average (arithmetic mean) of these n scores together with a score of 85 is 81.

 Quantity A Quantity B $$n$$ $$5$$

The average (arithmetic mean) of a set of n test scores is 80.
We can write: (sum of all n test scores)/n = 80
Multiply both sides by n to get: sum of all n test scores = 80n

The average (arithmetic mean) of these n scores together with a score of 85 is 81.
Once we add the score of 85 to the other n scores, we have a total of n+1 scores
So, we can write: (sum of the n test scores + 85)/(n + 1) = 81
Substitute to get: (80n + 85)/(n + 1) = 81
Multiply both sides of the equation by (n + 1) to get: 80n + 85 = 81(n + 1)
Expand: 80n + 85 = 81n + 81
Subtract 81 from both sides: 80n + 4 = 81n
Subtract 80n from both sides: 4 = n

We get:
QUANTITY A: 4
QUANTITY B: 5

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Brent Hanneson – Creator of greenlighttestprep.com Intern Joined: 24 Mar 2020
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Re: The average (arithmetic mean) of a set of n test scores is 8 [#permalink]
would you define this question as one of the hard ones?
GRE Instructor Joined: 10 Apr 2015
Posts: 3504
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Kudos [?]: 3935 , given: 63

Re: The average (arithmetic mean) of a set of n test scores is 8 [#permalink]
Expert's post
mike1917 wrote:
would you define this question as one of the hard ones?

IMO, it's more of a medium question. I'd place it in the 150 to 155 range.

Cheers,
Brent
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Brent Hanneson – Creator of greenlighttestprep.com Founder  Joined: 18 Apr 2015
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Re: The average (arithmetic mean) of a set of n test scores is 8 [#permalink]
Expert's post
The tag medium rather than hard comes directly from the book.

Of course, at the time a question like this was pretty hard but over time became medium.

The level has decreased.

Regards
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GRE Prep Club Members of the Month: Each member of the month will get three months free access of GRE Prep Club tests. Re: The average (arithmetic mean) of a set of n test scores is 8   [#permalink] 06 Apr 2020, 15:39
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