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counting and probability intermediate

Problem

Ben rolls four fair 10-sided dice, each numbered with numbers from 1 to 10. What is the probability that exactly two of the dice show a prime number?
Solution
The probability that a 10-sided die rolls a prime number is since the primes it can roll are 2, 3, 5, and 7. We can choose which dice show a prime number in ways. Then, there is a chance that the chosen dice will actually roll a prime number and the other dice won't. Therefore, the total probability that exactly two dice show a prime number is .
Final answer
\frac{216}{625}