stats -confidence intervals

stats -confidence intervals

A county is considering raising the speed limit on a road because they claim that the mean speed of vehicles is greater than 45 miles per hour.  A random sample of 25 vehicles has a mean speed of 48 miles per hour and a standard deviation of 5.4 mph. Find the 95% confidence interval for the speed limit. 

  1. Find the critical value

  2. Find the margin of error:  E

  3. Find the confidence interval: CI =

  4. Write the conclusion.