Answer:
For a data set of N elements:
{x₁, x₂, ..., xₙ}
The mean is:
The mean absolute deviation is:
And the population standard deviation is:
In this case, our set has 5 elements, and the set is:
{2, 4, 6, 9, 14}
The mean of this set is:
The mean absolute deviation is:
And the population standard deviation is:
Answer:
a) [24.114,29.2858]
b) Since 30 is not in the 95% confidence interval, there is a 95% probability that 30 is not the true mean WEP
Step-by-step explanation:
a)
The 95% confidence interval is given by the interval
where
= 26.7 is the sample mean
s = 17.7 is the sample standard deviation
n = 180 is the sample size
Since the sample size is big enough, we can use the Normal N(0,1) to compute and it would be 1.96(*) (a value such that the area under the Normal curve outside the interval [-z, z] is 5% (0.05))
and our 95% confidence interval is
(*)
This value can be computed in Excel with
<em>NORMINV(1-0.025,0,1)</em>
and in OpenOffice Calc with
<em>NORMINV(1-0.025;0;1)</em>
b)
Since 30 is not in the 95% confidence interval, there is a 95% probability that 30 is not the true mean WEP