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2.5 8.7 *** 9.6 4.6 *** 5.1 9.9 *** 10.0 6.0 10.3 *** 10.5 6.5 *** 6.6 11.6 8.5 12.0
Consider the sample of n = 20 scores. Notice that they are listed in order from 2.5 to 12.0,
but that some of the scores are obscured by ***. The mean, M, of these scores is 8.0. Suppose you are asked for the sample standard deviation of these scores. Since you don't have all of them, you cannot calculate it. Which of the following is the best estimate of the sample standard deviation?
a. 9.5
b. 0.5
c. 6.4
d. 2.7

Respuesta :

MrRoyal

Answer:

D. 2.7

Step-by-step explanation:

Given

[tex]Mean = 8.0[/tex]

[tex]n = 20[/tex]

[tex]Range = 2.5\ to\ 12.0[/tex]

Required

Estimate the standard deviation

Since, the given data has incomplete parameters, we can apply the range rule to estimate the standard deviation;

This is done as follows;

[tex]S.D = \frac{1}{4}(Max - Min)[/tex]

In this case:

[tex]Max = 12.0[/tex]

[tex]Min = 2.5[/tex]

So:

[tex]S.D = \frac{1}{4}(Max - Min)[/tex]

[tex]S.D = \frac{1}{4}(12.0 - 2.5)[/tex]

[tex]S.D = \frac{1}{4}(9.5)[/tex]

[tex]S.D = 2.375[/tex]

From the list of given option, the closest to 2.375 is 2.7;

Hence, the best estimate is 2.7

The correct option is D. 2.7

Given that,

  • The mean is 8.0.
  • the n = 20.
  • The range is from 2.5 to 12.0

The calculation is as follows:

The standard deviation should be

[tex]= \frac{1}{4} (12 - 2.5)\\\\ = \frac{1}{4} (9.5)[/tex]

= 2.375

= 2.7

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