Answer:
(34.15, 47.85)
Step-by-step explanation:
[tex]n = (\frac{z*stddev}{ME} )^{2}[/tex]
stddev = 11.9
z = invNorm(
area = (1 + confidence interval)/2
mean = 0
stddev = 1
)
= invNorm(
0.995
0
1
)
โ 2.576
n = 20
square root both sides
[tex]\sqrt{20} = 2.576 * 11.9 / ME[/tex]
multiply both sides by ME, divide both sides by โ20 to isolate ME
ME = 2.576 * 11.9/โ20
โ 6.85
interval = mean ยฑ ME
= (41-6.85, 41+6.85)
= (34.15, 47.85)