In a sample of 50 households, the mean number of hours spent on social networking sites during the month of january was 45 hours. in a much larger study, the standard deviation was determined to be 8 hours. assume the population standard deviation is the same. what is the 95% confidence interval for the mean hours devoted to social networking in january?

Step by step explanation pls for 10 pts the length of a rectangular board is 3 feet less than twice its width. a second rectangular board is such that each of its dimensions is the reciprocal of the corresponding dimensions of the first rectangular board. if the perimeter of the second board is one-fifth the perimeter of the first, what is the perimeter of the first rectangular board?