Please assist with the given roblem.
Scenario: 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:
Number of months before first raise in salary
CPA Inc. AB Int. Acct. Ltd. Pfisters
12 14 18 12
10 12 12 14
14 10 16 16
12 10
At the .05 level of significance, is there a difference in the mean number of months before a raise was granted among the four firms?