0.5 gallons plus 0.5 gallons plus 2 gallons plus 1gallon basicly i need to know how to add gallons.

Question 1 of 10 2 points different groups of 50 graduates of an engineering school were asked the starting annual salary for their first engineering job after graduation, and the sampling variability was low. if the average salary of one of the groups was $65,000, which of these is least likely to be the average salary of another of the groups? o a. $64,000 o b. $65,000 o c. $67,000 o d. $54,000