Answer:
A)CI 90 % = [ 7,2103 ; 8,7297]
B) s = √ ∑(xi - xp)²/n-1
c) z is the score for the given significance level in this case is 1,64
Step-by-step explanation:
For a confidence Interval of 90%, the significance level is α = 10 %
α = 0,1 α/2 = 0,05 and from z-table we find z(c) for 0,05 z(c) = 1,64
CI 90 % = [ x ± z(c) * s/√n ]
CI 90 % = [ 7,97 ± 1,64 * 2.62/√32]
CI 90 % = [ 7,97 ± 0,7597]
CI 90 % = [ 7,2103 ; 8,7297]
B) To calculate the standard deviation of the sample the equation is:
s = √ ∑(xi - xp)²/n-1
xi - xp is the difference between each one of the elements of the sample
xp is the mean or average of the elements of the sample and n is the sample size
