Question

A random sample of 11 health maintenance organizations (HMOs) was selected. For each HMO, the co-payment (in dollars) for a doctor's office visit was recorded. The results are as follows.33, 25, 49, 50, 35, 32, 44, 39, 47, 48, 30Send data to calculatorUnder the assumption that co-payment amounts are normally distributed, find a 95% confidence interval for the mean co-payment amount in dollars. Give the lower limit and upper limit of the 95% confidence interval. Carry your intermediate computations to at least three decimal places. Round your answers to one decimal place. (If necessary, consult a list of formulas.)Lower limit:Upper limit:

Answer 1

First, we have to calculate the mean and the standard deviation of the data,

sample mean = x-bar =39.273

sample std = s = 8.7646

Margin of error if confidence = 95%

`ME=(1.96*8.7646)/(√(11))=(17.1786)/(√(11))\approx5.1795`

So, the answers are

Lower limit: x-bar-ME=39.273-5.1795=33.4

Upper limit:x-bar+ME=39.273+5.1795=45.2