Respuesta :
Answer:
(80.4942, 94.9052)
Step-by-step explanation:
The sample mean is x = 87.7.
The sample standard deviation is s = 11.26.
At 99% confidence and 19 degrees of freedom, the critical value is t = 2.861.
The confidence interval is:
x ± t (s/√n)
87.7 ± 2.861 (11.26 / √20)
87.7 ± 7.2053
(80.4947, 94.9053)
The value of  confidence interval at 99% is (80.4942 , 94.9052) ,  Option D is the correct answer.
What is Mean ?
Mean is the measure of Central Tendency of the data set , It is measure by taking the sum of the data set and then dividing by the number of data.
It is given that
The sample mean is
= ∑( 82, 84, 98, 112, 97, 93, 91, 87, 112, 87, 79, 80, 72, 82, 94, 89, 89, 74, 80, 72 ) / 20
x = 87.7.
The sample standard deviation is
s = 11.26
It is asked to determine the confidence interval at 99% confidence
the critical value is t = 2.861.
n = 20
The confidence interval is given by
x ± t (s/√n)
Substituting the values in the equation
87.7 ± 2.861 (11.26 / √20)
87.7 ± 7.2052
80.4942 , 94.9052
Therefore the value of  confidence interval at 99% is (80.4942 , 94.9052) ,  Option D is the correct answer.
To know more about Mean
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