Sue invests £9000 in an account for one year.
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Answer: (23.53, 25.47)
Step-by-step explanation:
The confidence interval for population mean(when population standard deviation is unknown) is given by :-
, where = sample mean
n = sample size.
s = sample standard deviation.
t* = Critical value.
Given :
s= 4.4
Confidence level = 90% =0.090
Significance level =
Sample size : n= 58
Degree of freedom : df= n-1= 57
Using t-distribution table , the critical value :
Then, the confidence interval will be :-
Hence, a 90% confidence interval for the population mean = (23.53, 25.47)