Question
In: Statistics and Probability
A paint manufacturer wants to determine the average drying time of a new interior wall paint....
A paint manufacturer wants to determine the average drying time of a new interior wall paint. If for sample 12 test areas of equal size he obtained a mean drying time of 66.3 minutes and a standard deviation of 8.4 minutes, construct a 95% confidence interval for the true mean μ is (___ , ___). PLEASE SHOW ALL YOUR WORK
Solutions
Expert Solution
Solution :
Given that,
= 66.3
s =8.4
n = Degrees of freedom = df = n - 1 =12 - 1 = 11
At 95% confidence level the t is
= 1 - 95% = 1 - 0.95 = 0.05
/
2= 0.05 / 2 = 0.025
t
/2,df = t0.025,11 = 2.201 ( using student t table)
Margin of error = E = t/2,df
* (s /
= 2.201 * ( 8.4/
= 5.3
The 95% confidence interval mean is,
- E < 
<
+ E
66.3-5.3 <
< 66.3+5.3
61.0<
< 71.6
(61 , 71.6 )
orchestra answered 2 years agoRelated Solutions
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