Permutations and combinations

How many even numbers less than 500 can be formed using the digits 1, 2, 3, 4, 5? Each digit may be used only once in any number

• 12

• 16

• 18

• 20

Find the number of ways in which 12 people can be put into containing 3, 4, 5 people respectively

• 108900

• 27720

• 1320

• 174240

4-digit numbers are to be formed using four of the digits 2, 3, 7, 8, 9. Each digit may be used once only in any 4-digit number. Find how many digit number can be formed if the number is greater than 7000 and odd

• 84

• 21

• 168

• 42

A committee of 5 people is to be formed from 6 doctors, 4 dentists and 3 nurses. Find the number of different committees that could be formed if the committee contains at least 1 doctor

• 1266

• 211

• 1265

• 210

Given that ⁿP₅ = 6×(^n-1P₄), find the value of n

• 2

• 4

• 5

• 6