The formula for the confidence interval is given by
Sample mean + z*[σ/√n], and
Sample mean - z*[σ/√n]
We have:
Sample mean = 23.95
n = 40
σ = 2.55
z* for 99% confidence = 2.58
Substitute these values into the formula, we have
23.95 + (2.58)(2.55÷√40) = 24.99
23.95 - (2.58)(2.55÷√40) = 22.91
So the lower interval is 22.91 and the highest interval is 24.99
Step-by-step explanation:
-8 - -4= -8+4=-4
16- -4=20
8- -4=12
-9--4=-5
