Answer:
b)
The confidence interval for this case is given (6.21, 6.59)
So we can conclude at 95% of confidence that the true mean for the PH concentration is between 6.21 and 6.59 moles per liter
c) Since the confidence interval not contains the value 7 we reject the hypothesis that the true mean is equal to 7. And the same result was obtained with the t test for the true mean.
Explanation:
We assume that part a is test the claim. And we can conduct the following hypothesis test:
Null hypothesis:
Alternative hypothesis
The statistic is to check this hypothesi is given by:
We know the following info from the problem:
Replacing we got:
And the p value would be:
Since the p value is very low compared to the significance assumed of 0.05 we have enough evidence to reject the null hypothesis that the true mean is equal to 7 moles/liter
Part b
The confidence interval is given by:
The confidence interval for this case is given (6.21, 6.59)
So we can conclude at 95% of confidence that the true mean for the PH concentration is between 6.21 and 6.59 moles per liter
Part c
Since the confidence interval not contains the value 7 we reject the hypothesis that the true mean is equal to 7. And the same result was obtained with the t test for the true mean.