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What is the standard deviation of the values of the 20 coins in a

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Skywalker18
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What is the standard deviation of the values of the 20 coins in a [#permalink] New post  20 Jun 2016, 10:09
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What is the standard deviation of the values of the 20 coins in a certain jar ?

1. The average (arithmetic mean ) value of the coins in the jar is 25 cents .

2. All 20 coins in the jar have the same value .
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Re: What is the standard deviation of the values of the 20 coins in a [#permalink] New post  21 Jun 2016, 06:19
B.

2)same value means SD=0.

for 1)each value of coin is not given(not Suff)
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Re: What is the standard deviation of the values of the 20 coins in a [#permalink] New post  21 Jun 2016, 09:57
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Skywalker18 wrote:
What is the standard deviation of the values of the 20 coins in a certain jar ?

1. The average (arithmetic mean ) value of the coins in the jar is 25 cents .

2. All 20 coins in the jar have the same value .



1. The average (arithmetic mean ) value of the coins in the jar is 25 cents . We don't know other values to find out standard deviation. Not Sufficient.

2. All 20 coins in the jar have the same value . All the values are same means SD is 0. Sufficient

B is the answer
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Re: What is the standard deviation of the values of the 20 coins in a [#permalink] New post  01 Jul 2016, 19:32
This is tagged as a 600 - 700 level question, but it seems much easier than that. Sub 600 at best.
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Bunuel
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Re: What is the standard deviation of the values of the 20 coins in a [#permalink] New post  02 Jul 2016, 03:55
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pourts wrote:
This is tagged as a 600 - 700 level question, but it seems much easier than that. Sub 600 at best.


The difficulty level is calculated automatically based on the timer stats from the users which attempted the question.
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Re: What is the standard deviation of the values of the 20 coins in a [#permalink] New post  19 Jan 2018, 08:00
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Skywalker18 wrote:
What is the standard deviation of the values of the 20 coins in a certain jar ?

1. The average (arithmetic mean ) value of the coins in the jar is 25 cents .

2. All 20 coins in the jar have the same value .



Target question: What is the standard deviation of the values of the 20 coins in a certain jar ?

Statement 1: The average (arithmetic mean ) value of the coins in the jar is 25 cents .
There are several cases that satisfy statement 1. Here are two:
Case a: All 20 coins are quarters (each is worth $0.25). This meets this condition that the average value is 25 cents. In this case, the standard deviation EQUALS 0
Case b: The 20 coins are NOT all quarters. In this case, the standard deviation does NOT equal 0
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: All 20 coins in the jar have the same value
The means the standard deviation EQUALS 0
Since we can answer the target question with certainty, statement 2 is SUFFICIENT

Answer: B

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Re: What is the standard deviation of the values of the 20 coins in a [#permalink] New post  18 Dec 2018, 21:24
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Standard deviation of a set of numbers is a non-negative quantity which equals (maximum number – minimum number) in the set.
Statement 1: We are given the mean of the set of numbers. We can’t find the maximum and the minimum number from this information .Hence, Insufficient.
Statement 2: It is given that all 20 coins in the jar have the same value. This means the S.D = 0.
Hence, Sufficient.
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Re: What is the standard deviation of the values of the 20 coins in a [#permalink] New post  12 Jan 2019, 21:31
Standard deviation of a set of numbers is a non-negative quantity which equals zero, if and only if all the values in the set are numerically equal.
Statement 1: We are given the mean of the set of numbers. We can’t find the standard deviation from this information alone. Hence, Insufficient.
Statement 2: It is given that all 20 coins in the jar have the same value. This definitely implies thatstandard deviation equals zero. Hence, Sufficient.
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Re: What is the standard deviation of the values of the 20 coins in a [#permalink] New post  09 Jun 2019, 10:53
I think the thing to remember for this question is that if the quarter were the most valuable coin in existence, then the answer would be D. When I first read the question, I thought the answer was D, but then remembered the fifty cent piece exists.
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Re: What is the standard deviation of the values of the 20 coins in a [#permalink] New post  03 Aug 2019, 11:06
Skywalker18 wrote:
What is the standard deviation of the values of the 20 coins in a certain jar ?

1. The average (arithmetic mean ) value of the coins in the jar is 25 cents .

2. All 20 coins in the jar have the same value .


Standard deviation is measured by the deviation from the mean.
From statement 1 , we know the only average value of the coins.
And not each individual value.

From statement 2 , we can infer that the mean is same as each individual value . So the deviation from the mean is zero. So the standard deviation is zero.

Please give me kudo s if you liked my explanation.
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Re: What is the standard deviation of the values of the 20 coins in a [#permalink] New post  22 Aug 2020, 07:28
Bunuel ; this is a GMATprep question. Could you please change the source?
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Re: What is the standard deviation of the values of the 20 coins in a [#permalink] New post  22 Aug 2020, 08:09
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Kritisood wrote:
Bunuel ; this is a GMATprep question. Could you please change the source?


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Re: What is the standard deviation of the values of the 20 coins in a [#permalink] New post  22 Aug 2020, 18:28
Skywalker18 wrote:
What is the standard deviation of the values of the 20 coins in a certain jar ?

1. The average (arithmetic mean ) value of the coins in the jar is 25 cents .

2. All 20 coins in the jar have the same value .


target to determine SD
#1
The average (arithmetic mean ) value of the coins in the jar is 25 cents
no info about total coins ; value of each coin also not know insufficient
#2
All 20 coins in the jar have the same value
for a set which have same value the SD of the set is always zero ,0 .
sufficient
OPTION B
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