Answer
$x±2s, k=2, 1-\frac{1}{2^2} = 3/4*100 = 75%$
$74±2(12) = [50,98]$
$x±2.5s, k=2.5, 1-\frac{1}{2.5^2} = (1-0.16) \times100 = 84%$
$74±2.5(12) = [44, 104]$
$x±3s, k=3, 1-\frac{1}{3^2} = (1-1/9)\times100 = 88.89%$
$74±3(12) = [38, 110]$
Work Step by Step
$x±2s, k=2, 1-\frac{1}{2^2} = 3/4*100 = 75%$
$74±2(12) = [50,98]$
$x±2.5s, k=2.5, 1-\frac{1}{2.5^2} = (1-0.16) \times100 = 84%$
$74±2.5(12) = [44, 104]$
$x±3s, k=3, 1-\frac{1}{3^2} = (1-1/9)\times100 = 88.89%$
$74±3(12) = [38, 110]$
