<PRE><B>Question 862168</B>
the formula used would be the permutation formula of nPx.
n is the number of total seats on the bus.
x is the number of those seats you want to occupy at one time.
the formula for nPx is:
nPx = n! / (n-x)!
in your problem, n is equal to 12 and x is equal to 10.
the formula becomes:
12P10 = 12! / (12-10)! which is equal to 12! / 2! which is equal to 239,500,800.
the permutation formula is used because the seat that is assigned to each student can be different for each possible combination of 10 seats out of the 12.
for example:
1 combination of the seats could be seats 1,2,3,4,5,6,7,8,9,10
for that one combination of seats, the students in those seats could be arranged in 10! ways.
the permutation formula takes care of the total possible combination of seats and the position of the students within those seats.







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