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# The results of a certain experiment included 6 data values

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Manager
Joined: 06 Apr 2010
Posts: 133
The results of a certain experiment included 6 data values  [#permalink]

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23 Jun 2010, 12:30
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Difficulty:

25% (medium)

Question Stats:

78% (00:52) correct 22% (00:53) wrong based on 169 sessions

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The results of a certain experiment included 6 data values that were all multiples of the same number c, namely, c, 8c, 2c, 5c, 4c, and 4c. Was the average (arithmetic mean) of the 6 data values greater than 8?

(1) c < 4
(2) c > 2
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Posts: 49323
Re: Need Solution for some DS problems from SET1  [#permalink]

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23 Jun 2010, 15:31
2
udaymathapati wrote:
I have problem in solving following DS questions from SET1 (I don't know the source of this). Can anyone help me in resolvign them?

DS Questions: Need help

Q21:
The results of a certain experiment included 6 data values that were all multiples of the same number c, namely, c, 8c, 2c, 5c, 4c, and 4c. Was the average (arithmetic mean) of the 6 data values greater than 8?
(1) c < 4
(2) c > 2

$$Average=\frac{sum \ of \ terms}{# \ of \ terms}=\frac{c+8c+2c+5c+4c+4c}{6}=4c$$. Question: is $$4c>8$$? --> is $$c>2$$?

(1) c < 4. Not sufficient.
(2) c > 2. Sufficient.

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Re: Need Solution for some DS problems from SET1  [#permalink]

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23 Jun 2010, 15:49
udaymathapati wrote:
I have problem in solving following DS questions from SET1 (I don't know the source of this). Can anyone help me in resolvign them?

DS Questions: Need help

Q21:
The results of a certain experiment included 6 data values that were all multiples of the same number c, namely, c, 8c, 2c, 5c, 4c, and 4c. Was the average (arithmetic mean) of the 6 data values greater than 8?
(1) c < 4
(2) c > 2

I want to advice you. Please do not get me wrong, this was an easy question. On real Gmat you will face tricky DS quant questions. I think you need to brush up your quant concepts using MGMAT guides, especially Number properties. Its good to build concepts first. After that start practicing.
I wish you good luck.
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Re: The results of a certain experiment included 6 data values  [#permalink]

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10 Jul 2015, 16:15
2
Hi All,

Certain DS questions become easier to deal with if you 'rewrite' the question (as Bunuel showed in his explanation). For this prompt, you do not have to do that work to get the correct answer, but you will have to do some basic math regardless of how you approach the prompt.

Here, we're asked if the average of 6 terms (C, 8C, 2C, 5C, 4C and 4C) is greater than 8. This is a YES/NO question. Since the two Facts give us inequalities to work with, we can use each of them (individually) to figure out whether the average has a maximum or minimum possibility.

Fact 1: C < 4

We can use C = 4 as our "upper boundary"; in this case, the average of the 6 terms would be...

(4+32+8+20+16+16)/6 = 96/6 = 16

Since C is LESS than 4, the average of these 6 terms is LESS than 16.

IF....the average = 15, then the answer to the question is YES.
IF....the average = 0, then the answer to the question is NO.
Fact 1 is INSUFFICIENT

Fact 2: C > 2

Much as we did in Fact 1, we can use C = 2 as our "lower boundary"; in this case, the average of the 6 terms would be...

(2+16+4+10+8+8)/6 = 8

Since C is GREATER than 2, the average of these 6 terms is GREATER than 8.

Since the question asks if the average is greater than 8, the answer to the question is ALWAYS YES.
Fact 2 is SUFFICIENT.

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Re: The results of a certain experiment included 6 data values  [#permalink]

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01 Jul 2018, 18:55
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