A study of two hundred teens found that the number of hours they spend on social networking sites each week is normally distributed with a mean of 12 hours. The population standard deviation is 4 hours. What is the margin of error for a 98% confidence interval?

0.122

0.659

0.295

0.313

Question

A study of two hundred teens found that the number of hours they spend on social networking sites each week is normally distributed with a mean of 12 hours. The population standard deviation is 4 hours. What is the margin of error for a 98% confidence interval? 

 0.122 

 0.659 

 0.295 

 0.313

anonymous · Answer

The probability that a train leaves on time is 0.8. The probability that the train arrives on time and leaves on time is 0.24. What is the probability that the train arrives on time, given that it leaves on time? 

 0.3 

 0.8 

 0.16 

 0.24 

@mosaic is it 0.3 or 0.16

anonymous · Answer

First one is .659...