Question

In a survey of 280 adults over 50, 75% said they were taking vitamin supplements. Find the margin of error for this survey if we want a 99% confidence in our estimate of the percent of adults over 50 who take vitamin supplements. (Round to the nearest thousandths.)

Answer 1

Solution :

Given that,

Point estimate = sample proportion = = 0.75

1 - = 0.25

n = 280

Z_/2 = 2.576

Margin of error = E = Z _{/ 2} * (( * (1 - )) / n)

= 2.576 * (((0.75 * 0.25) / 280)

= 0.067

Margin of error = 0.067