Question

Hoping to lure more shoppers downtown, a city builds a new public parking garage in the central business district. The city plans to pay for the structure through parking fees. During a two-month period (44 weekdays), daily fees collected averaged $1,264 with a standard deviation of $150. What is a 90% confidence interval for the mean daily income this parking garage will generate

Answer 1

$1226.78<x<$1301.22

Explanation:

The formula for calculating confidence interval is expressed as;

CI = xbar ± z×(s/√n)

Given

Mean (xbar) = $1264

z is the z score at 90% CI = 1.645

s is the standard deviation = $150

n is the sample size = 44

Substitute

CI = 1264±1.645(150/√44)

CI = 1264±1.645(150/6.63)

CI = 1264±1.645(22.624)

CI = 1264±37.22

CI = (1264-37.22, 1264+37.22)

CI = (1226.78, 1301.22)

Hence the confidence interval of the mean is $1226.78<x<$1301.22