Question

The following intervals were confidence intervals for a given sample. Find the point estimate and margin of error in each case.

a. from .72 to .78

b. from .47 to .57

Answer 1

Solution :

a) Point estimate = = (Lower confidence interval + Upper confidence interval ) / 2

Point estimate =   = (0.72 + 0.78) / 2 = 0.75

Margin of error = E = Upper confidence interval - =

Margin of error = E = 0.78 - 0.75 = 0.03

b) Point estimate = = (Lower confidence interval + Upper confidence interval ) / 2

Point estimate =   = (0.47 + 0.57) / 2 = 0.52

Margin of error = E = Upper confidence interval - =

Margin of error = E = 0.57 - 0.52 = 0.05