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order to estimate the average time spent on the computer terminals per student at a university, data were collected for a sample of 81 business students over a one week period. Assume the population standard deviation is 1.8 hours. With a 0.95 probability, the margin of error is approximately a. 0.20 b. 0.39 c. 1.96 d. 1.64

Sagot :

Using the z-distribution, as we have the standard deviation for the population, the margin of error is given by:

b. 0.39.

What is a t-distribution confidence interval?

The confidence interval is:

[tex]\overline{x} \pm z\frac{\sigma}{\sqrt{n}}[/tex]

In which:

  • [tex]\overline{x}[/tex] is the sample mean.
  • z is the critical value.
  • n is the sample size.
  • [tex]\sigma[/tex] is the standard deviation for the sample.

The margin of error is given by:

[tex]M = z\frac{\sigma}{\sqrt{n}}[/tex]

In this problem, we have a 95% confidence level, hence[tex]\alpha = 0.95[/tex], z is the value of Z that has a p-value of [tex]\frac{1+0.95}{2} = 0.975[/tex], so the critical value is z = 1.96.

As for the other parameters, we have that [tex]\sigma = 1.8, n = 81[/tex].

Hence, the margin of error is given by:

[tex]M = z\frac{\sigma}{\sqrt{n}}[/tex]

[tex]M = 1.96\frac{1.8}{\sqrt{81}}[/tex]

[tex]M = 0.39[/tex]

Hence option b is correct.

More can be learned about the z-distribution at https://brainly.com/question/25890103