The local branch of IRS showed that on a sample of 10 customers it spent an average of 21 minutes and standard deviation of 5.6 minutes preparing tax returns. A volunteer tax preparer showed that on sample of 14 customers it spent an average of 27 minutes and standard deviation of 4.3 minutes preparing tax returns. Is there difference in the average time spent by two services? Employ a 1% significance level and critical value approach. Suppose normal distributions.