13.A senior accounting major at Midsouth State University has job offers from four CPA firms. To explore the offers further, she asked a sample of recent trainees how many months each worked for the firm before receiving a raise in salary. The sample information is submitted to Minitab with the following results:

anaylsis of variance:

sourceDFSSMSFP

Factor332.3310.782.360.133

Error1045.674.57

total1378.00

At the .05 level of significance, is there a difference in the mean number of months before a raise was granted among the four CPA firms?