o For example, consider question #1 from the practice questions. A gas utility company wishes to know how much time is needed for the serviceperson to handle a service call. A random sample of 16 gave an average time = 62.2 minutes with a standard deviation of 5 minutes. The 95% C for the mean service call time is? n The rst thing you must notice is that o is not given. The question only gives you the mean and S of the sample! So you cannot use a 2* condence interval. You must use at condence interval with n -l degrees of freedom. * Now just plug the values into the formula you need to memorize: ' Cases\" iii a 3 $ '3??? :3 ' Coggeg : 622 i 2 l3i W 351%