Answer
We are 99% confident that the mean price of a 4 GB flash memory card is between $\$12.975$ and $\$17.789$.
Work Step by Step
Here we have n = 10, df = n-1 = 9, x̅ = 15.382 and s = 2.34
Confidence = 99%
α = 1 - 0.99 = 0.01, α/2 = 0.005, $t_{α/2} = 3.25$
$E = 3.25 \times \frac{2.34}{\sqrt 10} = 2.407 $
Lower Bound = x̅ - E = 15.382 - 2.407 = 12.975
Upper Bound = x̅ + E = 15.382 + 2.407 = 17.789
