Assumes that monthly returns are normally distributed with a
Solution
Note that
Margin of Error E = t(alpha/2) * s / sqrt(n)
Lower Bound = X - t(alpha/2) * s / sqrt(n)
Upper Bound = X + t(alpha/2) * s / sqrt(n)
where
alpha/2 = (1 - confidence level)/2 = 0.025
X = sample mean = 1
t(alpha/2) = critical t for the confidence interval = 2.06865761
s = sample standard deviation = 4
n = sample size = 24
df = n - 1 = 23
Thus,
Margin of Error E = 1.689051866
Lower bound = -0.689051866
Upper bound = 2.689051866
Thus, the confidence interval is
( -0.689051866% , 2.689051866% ) [ANSWER]
