Answer:
a
,
b
c
Step-by-step explanation:
From the question we are are told that
The sample data is 21, 14, 13, 24, 17, 22, 25, 12
The sample size is n = 8
Generally the ample mean is evaluated as
Generally the standard deviation is mathematically evaluated as
considering part b
Given that the confidence level is 90% then the significance level is evaluated as
Next we obtain the critical value of from the normal distribution table the value is
The margin of error is mathematically represented as
=>
=>
The 90% confidence interval is evaluated as
substituting values
considering part c
Given that the confidence level is 95% then the significance level is evaluated as
Next we obtain the critical value of from the normal distribution table the value is
The margin of error is mathematically represented as
=>
=>
The 95% confidence interval is evaluated as
substituting values