Understanding Combinations and Factorials

What is the main focus of this video tutorial?

• Finding unknown values in combinations

• Finding the value of n in permutations

• Solving algebraic equations

• Understanding factorials in probability

What is the formula for combinations?

• (n-r)! / n!

• n! * r!

• n! / (n-r)! * r!

• n! / (n-r)!

In the problem where nC3 = 35, what is the value of n?

• 5

• 8

• 6

• 7

What is the value of 3 factorial (3!)?

• 9

• 12

• 3

• 6

In the problem where nC2 = 78, what is the value of n?

• 13

• 14

• 11

• 12

What are the two consecutive numbers that multiply to 156 in the nC2 = 78 problem?

• 12 and 13

• 13 and 14

• 14 and 15

• 15 and 16

In the problem where 10Cr = 120, what is one possible value of r?

• 2

• 3

• 4

• 5

In the problem where 11Cr = 165, what is one possible value of r?

• 8

• 5

• 6

• 7

What is the value of 6 factorial (6!)?

• 360

• 840

• 120

• 720

What is the relationship between 10C3 and 10C7?

• They are equal

• 10C7 is greater

• 10C3 is greater

• They are unrelated