Assume that all grade-point averages are to be standardized on a scale between 0 and 6. how many grade-point averages must be obtained so that the sample mean is within 0.006 of the population mean? assume that a 98% confidence level is desired. if using the range rule of thumb, sigma can be estimated as startfraction range over 4 endfraction equalsstartfraction 6 minus 0 over 4 endfraction equals1.5. does the sample size seem practical?