Answer:
And we are 95% confident that the true mean of chloride concentration is between 0.375 and 0.377 cc/ cubic meter
Step-by-step explanation:
Data provided
represent the sample mean for the chloride concentration
population mean (variable of interest)
s=0.0012 represent the sample standard deviation
n=15 represent the sample size
Confidence interval
The confidence interval for the mean is given by the following formula:
(1)
Since we need to find the critical value first we need to begin finding the degreed of freedom
The Confidence is 0.95 or 95%, the significance would be
and
, and the critical value for this case with a t distribution with 14 degrees of freedom is
And the confidence interval is:
And we are 95% confident that the true mean of chloride concentration is between 0.375 and 0.377 cc/ cubic meter
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Answer:
a. True
Step-by-step explanation:
By ∝= 5% we mean that there are about 5 chances in 100 of incorrectly rejecting a true null hypothesis. To put it in another way , we say that we are 95% confident in making the correct decision.
In the given question the null hypothesis is
H0: u ≤ 1 hour and Ha: u > 1 hour
So there is a 5% chance that the erroneous conclusion will be made that students spend on average more than 1 hour per assignment.
The given statement is true.
To grandparents house :
140/56 = 2.5 hours
Return trip :
140/50 = 2.8 hours
Total time : 2.8+2.5 = 5.3 hours