Permutations: Distinct Objects

How many ways can four friends be arranged in a row for a photograph?

• 120

• 24

• 16

• 4

What is the formula for permutations of n distinct objects taken r at a time?

• n^r

• n!/(n-r)!

• n!/(r!)

• n!/(n-r)!r!

If n = 5, what is the value of 5P3?

• 20

• 120

• 10

• 60

What is the value of n in the equation nP3 = 60?

• 6

• 5

• 4

• 3

When repetition is allowed, how many four-digit codes can be generated from the digits 1, 3, 5, 7, and 9?

• 3125

• 625

• 5000

• 1024

How many ways can three horses graze in a field divided into seven areas, with no two horses in the same area?

• 210

• 343

• 720

• 504

How many three-letter words can be formed from the letters in 'April' without repeating any letters?

• 10

• 20

• 60

• 120

How many security passwords of five characters can be generated from a set of seven distinct characters without repetition?

• 5040

• 2520

• 720

• 1440

How many three-digit numbers greater than 99 can be formed using the digits 2, 4, 6, and 8 with repetition allowed?

• 64

• 81

• 256

• 512

How many car number plates can be created with the format 'AB' followed by four digits, where repetition is allowed but not all digits can be zero?

• 9999

• 9998

• 10001

• 10000