For Exercises 29–49, assume normality and use Welch's test and interval unless otherwise indicated.
29. PC Sales. A personal computer company launched an advertising campaign in the hopes of boosting sales. A random sample (sample 1) of 16 days before the advertising blitz showed mean sales of 120 computers per day with a standard deviation of 30. A random sample (sample 2) of 15 days after the advertisements appeared showed mean sales of 125 computers per day with a standard deviation of 35. If it is appropriate, test whether . If not, explain why not.
10.2.29
Since both sample sizes are less than 30 and the distribution of both populations is unknown, it is not appropriate to use Welch's test.