The sample mean is 5.75 cars per week.
There are 65 salespeople interviewed and they sold various number of cars.
The sample mean would be the total number of cars sold divided by the number of sales people:
= Total number of cars sold / Number of salespeople
= ( (14 x 4) + (19 x 5) + (12 x 6) + ( 9 x 7) + (11 x 8) ) / 65
= 374 / 65
= 5.75 cars per week
On average, 5.75 cars are sold per week by the salespeople.
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