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A principle at a certain high school claims that the students in her school are above average in SAT. She collects a random sample of 50 students and given an SAT test that provided with a mean score of 541. Is there sufficient evidence statistically to support the principal’s claim? The mean population SAT score is 500 with a standard deviation of 100. SAT scores are normally distributed. Please show all the steps involved in a hypothesis testing including proper statistical symbols, formula used, and report/interpret results in complete sentences.

Sagot :

Using the z-distribution, it is found that since the value of the test statistic is greater than the critical value for the right-tailed test, there is sufficient evidence to support the principal’s claim.

At the null hypothesis, it is tested if they are not above average, that is, their mean is of 500 or below, hence:

[tex]H_0: \mu \leq 500[/tex]

At the alternative hypothesis, it is tested if they are above average, that is, their mean is of more than 500, hence:

[tex]H_1: \mu > 500[/tex]

We have the standard deviation for the population, thus, the z-distribution is used. The test statistic is given by:

[tex]z = \frac{\overline{x} - \mu}{\frac{\sigma}{\sqrt{n}}}[/tex]

The parameters are:

  • [tex]\overline{x}[/tex] is the sample mean.
  • [tex]\mu[/tex] is the value tested at the null hypothesis.
  • [tex]\sigma[/tex] is the standard deviation of the sample.
  • n is the sample size.

For this problem, the values of the parameters are: [tex]\overline{x} = 541, \mu = 500, \sigma = 100, n = 50[/tex]

Hence, the value of the test statistic is:

[tex]z = \frac{\overline{x} - \mu}{\frac{\sigma}{\sqrt{n}}}[/tex]

[tex]z = \frac{541 - 500}{\frac{100}{\sqrt{50}}}[/tex]

[tex]z = 2.9[/tex]

The critical value for a right-tailed test, as we are testing if the mean is greater than a value, with the standard 0.05 significance level, is of [tex]z^{\ast} = 1.645[/tex].

Since the value of the test statistic is greater than the critical value for the right-tailed test, there is sufficient evidence to support the principal’s claim.

A similar problem is given at https://brainly.com/question/25728144

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