Jill is 4 years younger than half Janet’s age. If Janet is y years old, which expression describes how old Jill is?
1 answer:
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Answer: (0.465, 5.535)
Step-by-step explanation:
Formula to calculate the confidence interval (<em>when population standard deviation is unknown</em>) is given by :-
, where = sample mean.
s= sample standard deviation.
n= Sample size.
= critical value
By considering the given information , we have
s=0.75
n= 9
Significance level = [1-0.90=0.1]
By using students' t distribution -table , the critical value for 95% confidence level :
[Note: degree of freedom = n-1]
Now, the 90% confidence interval for the true mean weight of these Southern California avocados will be :
Hence, the required confidence interval =(0.465, 5.535)