You want to make a confidence interval for the true average price of regular, unleaded gas in Gainesville. A random sample of 5 gas stations reveals the following prices: 1.93 1.97 1.99 1.96 1.98 What is the standard error of the sample mean, x-bar? IMPORTANT: Keep all significant digits in your calculator until the very end.

Respuesta :

Answer:

Standard error = 0.01029

Step-by-step explanation:

Data provided in the question:

Sample size, n = 5

prices: 1.93, 1.97, 1.99, 1.96, 1.98,

Now,

The standard error is calculated using the formula :

Standard error = [tex]\sqrt{\frac{\sigma^2}{n}}[/tex]

Here,

σ² is the variance

Mean = [tex]\frac{\textup{ 1.93 + 1.97 + 1.99 + 1.96 + 1.98}}{\textup{5}}[/tex]

=  1.966

Data   Data - Mean       (Data - Mean)²

1.93        -0.036               0.001296

1.97        0.004               0.000016

1.99        0.024               0.000576

1.96        -0.006               0.000036

1.98        0.014               0.000196

=================================

               ∑(Data - Mean)² = 0.00212

thus,

Variance, σ² = [tex]\frac{\sum\textup{(Data-Mean)}^2}{\textup{n-1}}[/tex]

or

Variance, σ² =  [tex]\frac{0.00212}{\textup{5-1}}[/tex]

or

Variance, σ² = 0.00053

Therefore,

Standard error = [tex]\sqrt{\frac{0.00053}{5}}[/tex]

or

Standard error = √0.000106

or

Standard error = 0.01029

Finding the sample standard deviation and dividing by the sample size, it is found that the standard error of the sample mean is of 0.0103.

  • The sample standard deviation is the square root of the sum of the differences squared of each observation and the mean, divided by the one less than the number of values.
  • The sample mean is the sum of all values divided by the number of values.

The values are: 1.93, 1.97, 1.99, 1.96, 1.98.

The sample mean is:

[tex]\overline{x} = \frac{1.93 + 1.97 + 1.99 + 1.96 + 1.98}{5} = 1.966[/tex]

The sample standard deviation is:

[tex]s = \sqrt{\frac{(1.93-1.966)^2+(1.97-1.966)^2+(1.99-1.966)^2+(1.96-1.966)^2+(1.98-1.966)^2}{4}} = 0.0230[/tex]

The standard error is:

[tex]S_e = \frac{s}{\sqrt{n}} = \frac{0.0230}{\sqrt{5}} = 0.0103[/tex]

The standard error is of 0.0103.

A similar problem is given at https://brainly.com/question/22718960

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