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You roll two 4-sided number cubes. Let X be the sum of the numbers on the two cubes P(X=3)

You roll two 4-sided number cubes. Let X be the sum of the numbers on the two cubes-example-1
User Varius
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1 Answer

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Notice that, since we are rolling two dices, we are dealing with 2 independent events

Let's suppose that the numbers on each dice are 1,2,3,4.

Then, if we roll two dices, there are 16 possible pairs (in principle)

(1,1)

(1,2)

...

(1,4)

(2,1)

...

(4,4)

Each of those pairs is equally probably than the others

Know, we need to identify the pairs that add up 3:

(1,2) and (2,1) are the only possibilities

Finally, we obtain the probability:


P(x=3)=(2)/(16)=(1)/(8)=0.125

Which is none of the options.

Another possibility is that the dices are cubes:

So, the possible combinations that can be obtained by throwing 2 cubes are:

(1,1)...(1,6),(2,1),...(6,6) Which are 36 possible combinations

And there are only 2 combinations that add up to 3: (2,1),(1,2)

So, the probability of adding up 3 is:


P(x=3)=(2)/(36)=(1)/(16)=0.0625

User Aec
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