+1313 Ben rolls four fair 10-sided dice. What is the probability that exactly two of the dice show a prime number?
+129845 The chance that any die shows a prime number = 4/10......so we have
C(4,2) * (.4)^2 * (.6)^2 = 28/45 = about 62.22%
+561 I don't think that is the correct answer(I Think)
The probability that a 10-sided die rolls a prime number is (4/10) = (2/5) since the primes it can roll are 2, 3, 5, and 7. We can choose which dice show a prime number in 4C2 = 6 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 6 * 36/625 = 216/625 .
Art of Problem Solving Solution @above
My solution:
Do what CPhill did, C(4,2) * (.4)^2 * (.6)^2 = 216/625.
