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Re: What is the standard deviation of the values of the 20 coins in a
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21 Jun 2016, 09:57

1

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
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19 Jan 2018, 08:00

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Top Contributor

1

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

Re: What is the standard deviation of the values of the 20 coins in a
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18 Dec 2018, 21:24

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.

Re: What is the standard deviation of the values of the 20 coins in a
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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 &nbs
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12 Jan 2019, 21:31