A number cube is rolled, then what is the probability of rolling an odd number or a power of two?

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Answer 1 · 2016-02-11T02:38:50

The probability is #5/6#.

Probability is #(desired)/(all)#

Let's find the possible outcomes of rolling odd.

1,3,5 are all odd. We have 3 outcomes.

Now find the possible outcome of a power of 2.
2 is #2^1#, 4 is #2^2#. We have 2 DIFFERENT outcomes.

(If these outcomes overlapped, we would have to subtract to get unique outcomes. In this case, these outcomes are different)

Now, we find the total number of possible outcomes.
A dice has 6 different outcomes.

Now add up the desired outcomes, #3 + 2 = 5#

and so the probability is #5/6#