Answer
We are 95% confident that the mean number of shares of Pepsico traded per day in 2010 is between 5.29 million and 6.33 million.
Work Step by Step
Here we have n = 40, df = n-1 = 39, x̅ = 5.81 and s = 1.60
Confidence = 95%
α = 1 - 0.95 = 0.05, α/2 = 0.025, $t_{α/2} = 2.023$
$E = 2.023 \times \frac{1.60}{\sqrt39} = 0.518 $
Lower Bound = x̅ - E = 5.81 - 0.518 = 5.29
Upper Bound = x̅ + E = 5.81 + 0.518 = 6.33
