Arandom sample of 500 reports an average yearly income of $42,000 with a standard deviation of $1000. an estimate of the parameter at the 95% level is about $175 wide. in this research situationa. the alpha level is 1000. b. we can be 95% confident that the population mean is 42,000 ± 175. c. the sample mean is $175. d. the sample size is much too small to justify the use of estimation procedures. e. we can be 95% confident that the population mean is 42,000 plus or minus 87.50