35
examples
Example
A paint manufacture wants to determine the average drying time of a
new interior wall paint. If for 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 population mean
µ
.
Procedure
1
m
STAT2
2
4
(INTR)
c
(T)
b
(1-Smpl)
3
2
(VAR)
c
.jf
w
gg.d
w
i.e
w
bc
w
1
(None)
c
4
1
(CALC)
Result Screen
Thus, the 95% confidence interval for
µ
becomes 61.0<
µ
<71.6 .
