Question

Jamie had seven posters, but only three could fit on his closet door. How many different ways can he arrange the three posters out of the seven on his closet door?



A. 52.5
B. 210
C. 1260
D. 5,040

Answer 1

Answer:  210

Explanation:

Jamie has 7 choices for the first slot, then 6 choices for the next, and 5 choices for the final slot. Order matters. He has 7*6*5 = 210 permutations.

Alternatively you can use the nPr permutation formula with n = 7 and r = 3.

That formula is

$nPr = \frac{n!}{(n-r)!}$

The exclamation marks indicate factorials. For instance, 4! = 4*3*2*1 = 24.

Answer 2

Answer:

B. 210 is correct!

Step-by-step explanation:

I got it correct on the quiz.