Which of the following situations involve a permutation?
select all the correct answers.

a) determining how many different ways 7 runners can be assigned lanes on a track for a race

b) determining how many 5-letter passwords can be made using the word "graph."

c) determining how many different groups of 10 students can be chosen to go on a field trip from a group of 25 students

d) determining how many different ways to choose 3 employees from a group of 9 employees.

e) determining how many different seating charts can be made placing 6 people around a table

f) determining how many different ways 4 cashiers can be chosen to work from a group of 6 cashiers.

A, B, E

Step-by-step explanation:

Permutations are involved when order matters, as in lane assignment, passwords, and seating charts.

When the end result is a "group of 10 students", "3 employees", or "4 cashiers", clearly order does not matter. One student, employee, or cashier is as good as another in these cases.

(b) 240

step-by-step explanation:

first, we use the pythagorean formula using the given side lengths to find x. then we use x to find the side lengths. then we add the side lengths to find the perimeter.

pythagorean theorem formula:

a^2 + b^2 = c^2

(x - 20)^2 + (x - 40)^2 = x^2

x^2 - 40x + 400 + x^2 - 80x + 1600 = x^2

x^2 -120x + 2000 = 0

(x - 100)(x - 20) = 0

x - 100 = 0 or x - 20 = 0

x = 100 or x = 20

we see that the solution x = 20 must be discarded because it will give a negative side length and a side length of 0. the only valid solution is x = 100.

perimeter = sum of the lengths of the sides

perimeter = x + x - 20 + x - 40

perimeter = 3x - 60

replace x with 100.

perimeter = 3(100) - 60

perimeter = 300 - 60

perimeter = 240