Question

It is found that 42 trucks pass an intersection in an hour when 560 non-trucks pass in the same time. At the 91% level, what is the confidence interval and margin error?

Answer 1

Solution :

Given that,

n = 560

x = 42

Point estimate = sample proportion = = x / n =42/560=0.075

1 - = 1-0.075=0.925

At 91% confidence level
Z/2 = Z_{0.045 = 1.695}

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

= 1.695 (((0.075*0.925) / 560)

= 0.019