Probability of 4 being the minimum number of the three numbers selected = 6C210C3
Probability of 8 being the maximum number of the three numbers selected = 7C210C3
The probability of 4 being the minimum number and 8 being the maximum number = 310C3
Therefore, required probability is 6C210C3 + 7C210C3 - 310C3 = 1140