Answer:
Step-by-step explanation:
For this case we have the following data given:
2.3 3.1 2.8
1.7 0.9 4.0
2.1 1.2 3.6
0.2 2.4 3.2
Since the data are assumedn normally distributed we can find the standard deviation with the following formula:
And we need to find the mean first with the following formula:
And replacing we got:
And then we can calculate the deviation and we got:
Answer:
OR
(15.102, 15.498)
Step-by-step explanation:
The formula to find the confidence interval is given by :-
, where n is the sample size
= sample standard deviation.
= Sample mean
= Two tailed z-value for significance level of
.
Given : Confidence level = 95% = 0.95
Significance level =
sample size : n= 250 , which is extremely large ( than n=30) .
So we assume sample standard deviation is the population standard deviation.
thus ,
By standard normal distribution table ,
Two tailed z-value for Significance level of 0.05 :
Then, the 95% confidence interval for the mean credit hours taken by a student each quarter :-
Hence, the mean credit hours taken by a student each quarter using a 95% confidence interval. =(15.102, 15.498)