Question

An industrial company claims that the mean pH level of the water in a nearby river is 6.8. You randomly select 19 water samples and measure the pH of each. The data from the 19 water samples appeared to be unimodal and symmetric and had a mean pH level of 6.7 and a standard deviation of 0.24. Is this evidence that the mean pH level of the water in this river is not 6.8?

The null and alternative Hypotheses for the test are:

H_O : μ = 6.8

H_A : μ ≠ 6.8

Describe the population mean, μ, in context.

Group of answer choices

The mean pH level of this river.

The proportion of the pH level of the 19 water samples.

The proportion of the pH level of this river.

The mean pH level of the 19 water samples.

Answer 1

Solution:

This is a two tailed test.

The null and alternative hypothesis is,

Ho: 6.8

Ha: 6.8

The test statistics,

t =( - )/ (s /n)

= ( 6.7 - 6.8 ) / ( 0.24 / 19 )

= -1.816

P-value = 0.861

The p-value is p = 0.861 > 0.05, it is concluded that the null hypothesis is fail to rejected.

There is not sufficient  evidence that the mean pH level of the water in this river is not 6.8.

The mean pH level of this river.