`(t-test-one-sample x-bar sd n mu #:tails)`procedureGiven observed data with mean

`x-bar`, standard devation`sd`and number of observations`n`(`n < 30`), return the significance of the sample compared with the population mean`mu`.`#:tails`is one of:`':both`two-sided (default)`':positive`one-sided,`x-bar >= mu``':negative`one-sided,`x-bar <= mu`