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The average of several test scores is 80. After that average was calcu

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The average of several test scores is 80. After that average was calcu [#permalink]

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New post 12 Feb 2015, 06:08
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The average of several test scores is 80. After that average was calculated, one make-up exam was given. After the make-up exam was included with the other scores, the new average was 83. Were more than 4 tests given total?

(1) The score on the make-up exam was 98.
(2) Two students scored an 82.

Kudos for a correct solution.
[Reveal] Spoiler: OA

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Re: The average of several test scores is 80. After that average was calcu [#permalink]

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New post 12 Feb 2015, 07:32
We need to find the number of exams ....

Statement 1 :
Sufficient ... Total number of exams greater the 4

Refer attachment figure .... 6 exams are there in total
Attachment:
Score.PNG
Score.PNG [ 7.23 KiB | Viewed 1974 times ]


Statement 2 :

Knowing the number of students will not help us knowing the number of exams .


Hence the answer is A
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Re: The average of several test scores is 80. After that average was calcu [#permalink]

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New post 12 Feb 2015, 22:16
Hi All,

There's a big "issue" with this question - it's not clear what the "make up" exam actually constitutes. Is the make-up exam a replacement (meaning someone took the Test once, then took it again)? If it is a replacement, are both scores (the original and the make-up) included in the average or just the make-up score? If it's not a replacement, then is the make-up exam an entirely new Test that has no impact on the prior set of scores (other than raising the average score)?

These issues impact what the correct answer will be. The Official GMAT would not leave you wondering about these types of details.

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Re: The average of several test scores is 80. After that average was calcu [#permalink]

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New post 16 Feb 2015, 05:22
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Bunuel wrote:
The average of several test scores is 80. After that average was calculated, one make-up exam was given. After the make-up exam was included with the other scores, the new average was 83. Were more than 4 tests given total?

(1) The score on the make-up exam was 98.
(2) Two students scored an 82.

Kudos for a correct solution.


VERITAS PREP OFFICIAL SOLUTION

The correct answer is (A).

It helps to know that the Average = Sum / # of Terms. Plugging in what we’re given:

80 = Sum / x

80x = Sum

83 = Sum + Make-up Score / x + 1

83x + 83 = Sum + Make-up Score

Let’s substitute “80x” for the “Sum”:

83x + 83 = 80x + Make-up Score

3x + 83 = Make-up Score

To know information about the number of tests given, we need to know more about the Make-up Score. Statement (1) tells us it was 98:
3x + 83 = 98
3x = 15
x = 5. Sufficient. The answer is Yes.

If you chose (B), Statement (2) tells us the scores of two students, but it’s possible to get both a yes and a no with these numbers. We also need to know the make-up students’ score to find the total number of given tests.

If you chose (C), Statement (1) alone is sufficient. We can solve by setting up two equations with the same two variables and substituting.

If you chose (E), Statement (1) is sufficient. You may want to review the formula for mathematical mean, as well as the “n equations with n variables” concept.
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New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
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Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


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Re: The average of several test scores is 80. After that average was calcu [#permalink]

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Re: The average of several test scores is 80. After that average was calcu   [#permalink] 29 Mar 2017, 10:15
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