an engineer has designed a valve that will regulate water pressure on an automobile engine. the valve was tested on 170 engines and the mean pressure was 6.7 lbs/square inch. assume the standard deviation is known to be 1. if the valve was designed to produce a mean pressure of 6.6 lbs/square inch, is there sufficient evidence at the 0.05 level that the valve performs above the specifications? state the null and alternative hypotheses for the above scenario.

Respuesta :

There is sufficient data to infer that the valve does not operate as intended at the 0.1 level.

Null hypothesis: H₀ : μ = 7.6

Alternative hypothesis: Hₐ : μ ≠ 7.6

What is the Null hypothesis?

In inferential statistics, the null hypothesis states that two possibilities are equal.

The observed difference is thought to be the sole product of chance, which is the underlying premise.

Statistical tests can be used to calculate the likelihood that the null hypothesis is true.

So,

Null hypothesis: H₀ : μ = 7.6

Alternative hypothesis: Hₐ : μ ≠ 7.6

As the population standard deviation is given when n > 30

So, we'll run the Z test.

Formula: [tex]z=\frac{x-\mu}{\frac{a}{\sqrt{n}}}[/tex]

Replace the values:

[tex]\begin{aligned}& z=\frac{7.7-7.6}{\frac{11.6}{\sqrt{160}}} \\& z=2.449\end{aligned}[/tex]

For the p-value, see the z table.

Consequently, p = 0.9927.

The two-tailed nature of the test So, p = 2(1- 0.9927) = 0.0146

α = 0.1

p value< α

Thus, we disregard the null hypothesis.

Hence, at the 0.1 level, there is enough evidence to conclude that the valve does not function as intended.

Therefore, there is sufficient data to infer that the valve does not operate as intended at the 0.1 level.

Null hypothesis: H₀ : μ = 7.6

Alternative hypothesis: Hₐ : μ ≠ 7.6

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