A building manager installs sensor to see how ofter people og the lights whe they leave a room. After a month the manager has sample size of 625, a sample mean of 47% and a sample standard deviation of 5% what is the confidence level for a interval of 46.8% to 47.2%
A-85%
B-68%
C-95%
D-99.7%

Question

A building manager installs sensor to see how ofter people og the lights whe they leave a room. After a month the manager has sample size of 625, a sample mean of 47% and a sample standard deviation of 5% what is the confidence level for a interval of 46.8% to 47.2%
A-85%
B-68%
C-95%
D-99.7%

perl · Answer

do you have a formula for confidence interval

anonymous · Answer

X-2 o divited by square root og n  to x plus 2 o divited to square root of n

anonymous · Answer

because the interval is +/- 0.2

E= 0.2
StdDev=5
SampleSize=625
z= (E/StdDev)*SQRT(SampleSize)

Once you have the z you can convert it to your confidence level with

CL =( normsdist(z) - 0.5 ) * 2

the normsdist function is available in excel, openoffice or google spreadsheets, you can use that instead of a calculator if you dont have one.