In a probability experiment that records the sum of the numbers on the upper faces of the dice after they become stationary, the outcome with the greatest probability is...
That makes it a poor problem.
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The coefficients tell us the number of way we can get the various sums when four dice are used. For example the term tells us there are 146 ways to throw a fourteen.
You can change the power 4 in to find out the numbers for any number of dice.