Answer:
(26.2252 ; 27.3748)
Step-by-step explanation:
The confidence interval is given by :
x ± Margin of error
The margin of error = Zcritical * (σ/√(n))
σ = 7.5 ; n = 654
Zcritical = Zα/2 = 1.96
The margin of error = 1.96 * (7.5/√654) = 0.5748
The confidence interval :
Upper boundary = 26.8 + 0.5748 = 27.3748
Lower boundary = 26.8 - 0.5748 = 26.2252
(26.2252 ; 27.3748)
We are 95% confident that the mean BMI of the entire population will fall in between (26.2252 ; 27.3748)
