Question

A die is rolled twice. What is the probability of showing a 1 on the first roll and an even number on the second roll?

Durian

Answer 1

1/12

Explanation:

Okay, so this will be a compound probability question because there are two parts to the question.

Firstly, a die has 6 sides, and there is only one chance of getting a 1, so the probability would be 1/6.

Furthermore, there are 3 different even numbers on a 6-sided die, so that is 3/6, which can be simplified to 1/2.

Now, because this is a compound probability, we have to multiply 1/2 and 1/6 together, which would give us our answer of 1/12.

Answer 2

Answer: 1/12

Explanation:

The sample space when a die is rolled twice is given below:

1 2 3 4 5 6

1 1,1 1,2 1,3 1,4 1,5 1,6

2 2,1 2,2 2,3 2,4 2,5 2,6

3 3,1 3,2 3,3 3,4 3,5 3,6

4 4,1 4,2 4,3 4,4 4,5 4,6

5 5,1, 5,2 5,3 5,4 5,5 5,6

6 6,1 5,2 6,3 6,4 6,5 6,6

Those showing a one on the first throw and an even number on the second roll are:

{ 1,2 : 1,4 : 1,6}

Therefore :

the probability of showing a 1 on the first roll and an even number on the second roll = 3/36

= 1/12