We assume that the number cube and the coin are fair (e.g. the probabilities for each of the numbers on the cube is 1/6 and the probability of heads on the coin is 1/2.)
The probability of rolling an odd number on the cube is 1/2. (There are three outcomes in the event space: {1,3,5}, while the sample space has 6 items. The probability is the number of items in the event space divided by the number of items in the sample space or 3/6 which reduces to 1/2.
The probability of flipping heads is 1/2.
The probability of rolling an odd number and then flipping heads is (1/2)(1/2)=1/4 using the product principal.
The probability is 1/4 or .25
We could also list all of the possibilities: 1H 2H 3H 4H 5H 6H 1T 2T 3T 4T 5T 6T -- there are 12 items in the sample space. The event space is {1H,3H,5H}. Since there are 3 items in the event space, the probability is 3/12=1/4.
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