Question

Eduardo has a red 6-sided number cube and a blue 6-sided number cube. The faces of the cubes are numbered 1 through 6.

Eduardo rolls both cubes at the same time.

The random variable X is the number on the red cube minus the number on the blue cube.

What is P(−2≤X≤1)?

Answer 1

PLEASE HELP!!

Answer 2

The sample space has 36 possible combinations of numbers. These can be set out in column form as follows:
6,6 5,6 4,6 3,6 2,6 1,6
6,5 5,5 4,5 3,5 2,5 1,5
6,4 5,4 4,4 3,4 2,4 1,4
6,3 5,3 4,3 3,3 2,3 1,3
6,2 5,2 4,2 3,2 2,2 1,2
6,1 5,1 4,1 3,1 2,1 1,1
Let the left hand number in each pair be the number on the red cube. Looking at the first row in the above table, the pairs that meet the requirement given by the inequality are:
6,6 5,6 4,6
Next you need to find the qualifying pairs in each of the remaining rows. The required probability is found from:
\[\large \frac{number\ of\ qualifying\ pairs}{total\ number \ of\ pairs}\]

Answer 3

I don't get it :( ugh

Answer 4

If you look at the first pair in the top row of the table (6,6), 6 - 6 = 0. Zero is greater than -2 and less than 1, therefore zero qualifies as X and we have 1 pair out of the 36 possible pairs that qualifies.

Answer 5

Ok so I need to do the subtraction on all 36 numbers then add the results up?

Answer 6

I got 5/9 is that even right? UGH!

Answer 7

Yes, I get 5/9 also.