In order to estimate the mean amount of time computer users spend on the internet each month, how many computer users must be survyed in order to be 90% confident that your sample mean is within 12 minutes of the population mean? Assume that the standard deviation of the population of monthly time spent on the internet is 220 minutes. What is a major obstacle to getting a good estimate of the population mean? Use technology to find the estimated minium required sample size. The minimum sample size required is ? Computer users round to the nearest whole number. What is a major obstacle to getting a good estimate of the population mean?