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A children's clothing company sells hand-smocked dresses for girls. The length of one particular size of dress is designed to be 42 inches. The company regularly tests the lengths of the garments to ensure quality control, and if the mean length is found to be significantly longer or shorter than 42 inches, the machines must be adjusted. The most recent simple random sample of 23 dresses had a mean length of 38.88 inches with a standard deviation of 8.86 inches. Assume that the population distribution is approximately normal. Perform a hypothesis test on the accuracy of the machines at the 0.025 level of significance.

Step 1 of 3: State the null and alternative hypotheses for the test. Fill in the blank below.

[tex]\[
\begin{array}{l}
H_0: \mu = 42 \\
H_a: \mu \neq 42
\end{array}
\][/tex]

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[tex]$\ \textless \ $[/tex]
[tex]$\neq$[/tex]

Sagot :

To perform a hypothesis test to determine if the machines are producing dresses with the correct mean length, we begin by setting our null and alternative hypotheses. Here is the detailed step-by-step solution:

Step 1: State the hypotheses

1. Null Hypothesis (H₀): This is the statement that there is no effect or no difference, and it represents the status quo. For this problem, we are testing whether the mean length of the dresses is equal to the designed length of 42 inches.

[tex]\[ H_0: \mu = 42 \][/tex]

2. Alternative Hypothesis (Hₐ): This is the statement that reflects what we are trying to find evidence for. In this case, we want to test if the mean length of the dresses is different from 42 inches, which could mean it is either longer or shorter. This is a two-tailed test because we are considering both possibilities.

[tex]\[ H_a: \mu \neq 42 \][/tex]

So, the complete hypotheses are:

[tex]\[ \begin{array}{l} H_0: \mu = 42 \\ H_a: \mu \neq 42 \end{array} \][/tex]

This forms the basis for our hypothesis test to determine whether the machines are producing dresses with the correct mean length.