Meyer rolls two fair, ordinary dice with the numbers 1,2,3,4,5,6 on their sides. What is the probability that AT LEAST one of the dice shows a square number?

SmartMathMan
Jan 18, 2018

#1**+2 **

Meyer rolls two fair, ordinary dice with the numbers 1,2,3,4,5,6 on their sides. What is the probability that AT LEAST one of the dice shows a square number?

So one of the numbers must be 1 or 4

the posibilities are

P(1,anything) = (1/6)*1 = 1/6

P(4,anything) = 1/6

so

P(1, or 4 and any number on the other die) = 2/6

P(any number, 1 or 4) = 2/6

so together that is 4/6 trouble is some combinations have been added twice.

P(first die is 1 or 4, AND second die is 1 or 4) = 2/6 * 2/6 = 4/36

So the prob that you want will be 2/6 + 2/6 - 4/36 = 20/36 = 5/9

You can check it by counting them. To get all the combinations just do it in a 6 by 6 grid.

Melody
Jan 18, 2018