Question

In a survey, 28 people were asked how much they spent on their auto insurance. The results were roughly bell-shaped with a mean of $1092 and standard deviation of $183. Estimate how much typical drivers would spend on their auto insurances (use a 99% confidence level).

1. Enter your answer as an open-interval (i.e., parentheses) accurate to whole numbers.

   Confidence interval =

2. 
   
3. Express the same answer using the point estimate and margin of error. Give your answers to whole numbers.

Answer 1

Solution :

(a)

t _/2,df = 2.771

Margin of error = E = t_/2,df * (s /n)

= 2.771 * (183 / 28)

Margin of error = E = 96

The 99% confidence interval estimate of the population mean is,

- E < < + E

1092 - 96 < < 1092 + 96

996 < < 1188

(999 , 1188)

(b)

E

1092 96