If a McBurger employee is expected to work four of the seven days in a week, how many different weekly schedules are possible for the employee?
Please check my answer = 840
no,
Aren't we "choosing" 4 out of the 7 days
which is C(7,4) or 35
You must have done 7x6x5x4 = 840
That would include sets of the same 4 days, simply arranged in different order, such as MON SAT SUN WED in 4! ways, but only one of these would be a possible way to work (the days would have to be in the correct sequence)
So we have to divide your answer by 4! to get 840/24 = 35 , just like the C(7,4) gives us