In: Statistics and Probability
A random sample of 20 recent weddings in a country yielded a mean wedding cost of
$26,327.16
Assume that recent wedding costs in this country are normally distributed with a standard deviation of
$8,100
Complete parts (a) through (c) below.
a. Determine a 95% confidence interval for the mean cost,
muμ,
of all recent weddings in this country.
The 95% confidence interval is from ?????
(Round to the nearest cent as needed.)
Solution :
Given that,
= 26327.16
s = 8100
n = 20
Degrees of freedom = df = n - 1 = 20 - 1 = 19
a ) At 95% confidence level the t is ,
= 1 - 95% = 1 - 0.95 = 0.05
/ 2 = 0.05 / 2 = 0.025
t /2,df = t0.025,19 =2.093
Margin of error = E = t/2,df * (s /n)
= 2.093 * (8100/ 20) = 3791
The 95% confidence interval estimate of the population mean is,
- E < < + E
26327.16 - 3791< < 26327.16 + 3791
22536.16 < <301180.16
(25, 26 )