Question
5 a) How many even numbers can be formed from the digits 1, 2, 3, 4, 5?
b) How many of these numbers are greater than 3000?
b) How many of these numbers are greater than 3000?
Answers
mathhelper
You have conflicting restrictions, so take it in cases
To be greater than 3000, the number must start with either 4 or 5
case1 : it start with a 4, that means you have 1 choice to make it even, namely the 2
number of ways = 1*3*2*1*1 = 6
case2 : it starts with a 5, so you have 2 choices for the unit digit
number of ways = 1*3*2*1*2 = 12
So you have 18 such numbers
To be greater than 3000, the number must start with either 4 or 5
case1 : it start with a 4, that means you have 1 choice to make it even, namely the 2
number of ways = 1*3*2*1*1 = 6
case2 : it starts with a 5, so you have 2 choices for the unit digit
number of ways = 1*3*2*1*2 = 12
So you have 18 such numbers
Homeworktaker
can someone answer part a
Homeworktaker
A motorcycle licence plate consists of two or three letters followed by four digits. How many licence plates can be made?