Question

Permutations and, combinations: problem type 2.

Answer 1

Step-by-step explanation:

Permutations:

nP r = n!/(n + r)!

Combinations:

nCr = n!/(n - r)!r!

c - combination

p - permutations

Since in both the problems they are looking for different groups, it is a combination problem. the order in which the people were selected in each group is not important, what is required are different groups.

A.

n = 51

r = 3

51C 3 = 51! / ((51 - 3) ×3!)

51C3 = 20 825 groups

OR:

$c = \frac{51}{3} \times \frac{50}{2} \times 49$

$c = 20825$

B.

$c = \frac{14}{4} \times \frac{13}{3} \times \frac{12}{2} \times 11$

$c = 1001$