A sample of 100 information systems managers had an average hourly income of $40.00 with a standard deviation of $8.00. The 95% confidence interval for the average hourly wage (in $) of all information system managers is   a.  38.684 to 41.316.   b.  32 to 48.   c.  38.432 to 41.568.   d.  39 to 41

A researcher is interested in finding a 90% confidence interval for the mean number of times per day that college students text. The study included 115 students who averaged 34.2 texts per day. The standard deviation was 23.3 texts. a. To compute the confidence interval use a     distribution. b. With 90% confidence the population mean number of texts per day is between  and   texts. c. If many groups of 115 randomly selected members are studied, then a different confidence interval would be produced from each group. About  percent of these confidence intervals will contain the true population number of texts per day and about  percent will not contain the true population mean number of texts per day.