Answer
Lower Bound = 1.612, Upper Bound = 4.278
We are 95% confident that the standard deviation of the price of a 4 GB flash memory card is between 1.612 and 4.278 dollars.
Work Step by Step
Here n = 10, df = n-1 = 9, $s^{2} = 5.488$, Confidence Interval = 95%
α = 1 - 0.95 = 0.05, α/2 = 0.025, 1 - α/2 = 0.975
$χ2_{α/2} = 19.023$, $χ2_{1-α/2} = 2.700$
$\frac{(n-1)s^{2}}{χ2_{α/2}} < σ^{2} < \frac{(n-1)s^{2}}{χ2_{1-α/2}}$
$\frac{9 \times 5.488}{19.023} < σ^{2} < \frac{9 \times 5.488}{2.700}$
$ 2.6 < σ^{2} < 18.29$
1.612 < σ < 4.278
