A textile fiber manufacturer is investigating a new drapery yarn, which the company claims has a mean thread elongation of 12 kilograms with a standard deviation of 0.5 kilograms. The company wishes to test the hypothesis H0:μ=12 against H1:μ<12 using a random sample of n=4 specimens. Calculate the P-value if the observed statistic is x¯=11.5. Round your final answer to five decimal places (e.g. 98.76543).

Respuesta :

Answer:

P-value = 0.02275

Step-by-step explanation:

We are given the following in the question:

Population mean, μ =  12 kilograms

Sample mean, [tex]\bar{x}[/tex] = 11.5 kilograms

Sample size, n = 4

Alpha, α = 0.05

Population standard deviation, σ = 0.5 kilograms

First, we design the null and the alternate hypothesis

[tex]H_{0}: \mu = 12\\H_A: \mu < 12[/tex]

We use one-tailed(left) z test to perform this hypothesis.

Formula:

[tex]z_{stat} = \displaystyle\frac{\bar{x} - \mu}{\frac{\sigma}{\sqrt{n}} }[/tex]

Putting all the values, we have

[tex]z_{stat} = \displaystyle\frac{11.5 - 12}{\frac{0.5}{\sqrt{4}} } = -2[/tex]

We calculate the p-value from the standard z-table:

P-value = 0.02275

The p-value of the hypothsis 0.00135

Data;

  • Standard deviation = 0.5kg
  • mean elongation = 12kg
  • n = 4
  • Mean = 11.5

Null and Alternative Hypothesis

[tex]H_-o : \mu =12\\H_1 : \mu < 12[/tex]

Since the standard deviation = 0.5

Mean = 11.25, n = 4

Test statistic =

[tex]t = \frac{x -\mu}{\sigma / \sqrt{n} } \\t = \frac{11.25-12}{0.5/\sqrt{4} } \\t = -3[/tex]

The p-value = p(z < -3) = 0.00135

The p-value of the hypothsis 0.00135

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