Answer:
Margin of error = E = 40
Step-by-step explanation:
Assuming 99% confidence level
Given that x = 253.9
s.d = 63.6
n = 18
Degrees of freedom = df = n - 1 = 18 - 1 = 17
At 99% confidence level the t is, α = 1 - 99% = 1 - 0.99 = 0.01
α/2 = 0.01 / 2 = 0.005
t α/2,df = t,0.005 = = 2.680 (using student t table)
Margin of error = E = t α/2,df * (s.d/√n)
Margin of error = 2.680*63.6/√18
Margin of error = 2.680*63.6/4.242641
Margin of error = 2.680*14.99066265564303
Margin of error = 40.17
Margin of error = E = 40
