Alocal phone company charges a standard rate of three dollars per call. after 1 minute the charge was $4.50. after 2 minutes the rate is $6.00. susan has $10.00, how long can susan stay on her phone?

Do one of the following, as appropriate: (a) find the critical value z subscript alpha divided by 2 , (b) find the critical value t subscript alpha divided by 2 . 99%; nequals 17; sigma is unknown; population appears to be normally distributed.