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Consider the situation in which the health inspector finds the sample mean of the 4 pools to be outside the safe ph levels. As a result, the inspector declares that the population mean is not 7. 5. However, if the population mean really is 7. 5, the inspector will have made an error. Such an error is called a type i error. Find the probability that the inspector will make a type i error with the sample of 4 pools. Show your work.

Respuesta :

The probability of Type I error is the likelihood of finding a mean outside

the safe zone for the 4 pools.

  • The probability that the inspector will make a Type I error is 0.0026

What is a Type I error and what is the probability that it will occur?

In hypothesis testing, a Type I error is the error of rejecting a true null

hypothesis.

From a similar question, the possible parameters are;

The safe pH levels for swimming pools is between 7.2 and 7.8

The standard deviation is 0.2

The probability that the pH is within the safe zone is found as follows;

[tex]The \ z-score, \ Z = \mathbf{\dfrac{\overline x - \mu}{\dfrac{\sigma}{n} }}[/tex]

Which gives;

[tex]\mathbf{P \left(\dfrac{7.2 - 7.5}{\dfrac{0.2}{\sqrt{4} } } < \dfrac{\overline x - \mu}{\sigma} < \dfrac{7.8 - 7.5}{\dfrac{0.2}{\sqrt{4} }} \right)} = P(-3 < Z < 3)[/tex]

P(-3 < Z < 3) = P(Z < 3) - P(Z > -3) = P(Z < 3) - (1 - P(Z < 3))

P(Z < 3) - (1 - P(Z < 3) = 2·P(Z < 3) - 1

2·P(Z < 3) - 1 = 2 × 0.9987 - 1 = 0.9974

The probability that the swimming pool is not safe = 1 - (2·P(Z < 3) - 1)

1 - (2·P(Z < 3) - 1) = 1 - 0.9974 = 0.0026

Which gives;

  • The probability that the mean will be seen as not in the safe zone and therefore not 7.5 is 0.0026 and the probability that the inspector will make a Type I error is 0.0026

Learn more about hypothesis testing here:

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