A study of one thousand teens found that the number of hours they spend on social networking sites each week is normally distributed with a mean of 15 hours. The population standard deviation is 2 hours. What is the 95% confidence interval for the mean?
A. 14.88 - 15 hours
B. 14.88 - 15.12 hours
C. 15 - 15.12 hours
D. 14.76 - 14.24 hours

Question

A study of one thousand teens found that the number of hours they spend on social networking sites each week is normally distributed with a mean of 15 hours. The population standard deviation is 2 hours. What is the 95% confidence interval for the mean?
A. 14.88 - 15 hours
B. 14.88 - 15.12 hours
C. 15 - 15.12 hours
D. 14.76 - 14.24 hours

anonymous · Answer

Medal?!!!??

anonymous · Answer

@herua123 
@Hearfilia

anonymous · Answer

I got B

anonymous · Answer

and your welcome:)

anonymous · Answer

The length of a screw produced by a machine is normally distributed with a mean of 0.25 inches and a standard deviation of 0.01 inches. What percent of screws are between 0.24 and 0.26 inches?
A. 68%
B. 95%
C. 99.7%
D. 100%
I think its B.... is that correct??

anonymous · Answer

hmm it all depends what did you do to get B

anonymous · Answer

i guessed, it seems like the most reasonable answer:/

anonymous · Answer

go guys.XD i know you can do it.my statistical brain isn't working. Its almost 3 am here.(-_-)

anonymous · Answer

do you know if B is correct @IMStuck ??

anonymous · Answer

yes its correct

anonymous · Answer

thank you so much for your help

anonymous · Answer

your welcome anytime:)